EN ISO 9241-151:2008

Ergonomics of human-system interaction - Part 151: Guidance on World Wide Web user interfaces (ISO 9241-151:2008)

ISO 9241-151:2008 provides guidance on the human-centred design of software Web user interfaces with the aim of increasing usability. Web user interfaces address either all Internet users or closed user groups such as the members of an organization, customers and/or suppliers of a company or other specific communities of users.
The recommendations given in this part of ISO 9241:2008 focus on the following aspects of the design of Web user interfaces: high-level design decisions and design strategy; content design; navigation and search; content presentation.
The user interfaces of different types of user agents such as Web browsers or additional tools such as Web authoring tools are not directly addressed in this part of ISO 9241:2008 (although some of its guidance could apply to these systems as well).
Web user interfaces are presented on a personal computer system, mobile system or some other type of network‑connected device. While the recommendations given in this part of ISO 9241:2008 apply to a wide range of available front‑end technologies, the design of mobile Web interfaces or smart devices could require additional guidance not within its scope; neither does it provide detailed guidance on technical implementation nor on issues of aesthetic or artistic design.

Ergonomie der Mensch-System-Interaktion - Teil 151: Leitlinien zur Gestaltung von Benutzungsschnittstellen für das World Wide Web (ISO 9241-151:2008)

Dieser Teil von ISO 9241 enthält Anleitungen zur benutzerorientierten Gestaltung von Software-Benutzungs¬schnittstellen für Web-Anwendungen mit dem Ziel der Verbesserung der Gebrauchstauglichkeit. Web-Benutzungsschnittstellen richten sich entweder an alle Internetnutzer oder geschlossene Benutzer¬gruppen, wie z. B. die Mitglieder einer Organisation, Kunden und/oder Lieferanten eines Unternehmens oder andere spezifische Nutzergemeinschaften.
Die Empfehlungen in diesem Teil von ISO 9241 konzentrieren sich auf folgende Aspekte der Gestaltung von Web-Benutzungsschnittstellen:
   grundlegende Gestaltungsentscheidungen und -strategien;
   Gestaltung des Inhaltes;
   Navigation und Suche;
   Darstellung des Inhaltes.
Die Benutzungsschnittstellen bestimmter Benutzeragenten (wie Web-Browser) oder zusätzlicher Tools, wie z. B. Webautorentools werden nicht direkt in diesem Teil von ISO 9241 angesprochen, obwohl einige Richt¬linien auch für diese Systeme gelten könnten.
Web-Benutzungsschnittstellen werden auf einem PC-System, einem mobilen System oder anderen vernetz¬ten Geräten dargestellt. Während die in diesem Teil von ISO 9241 gegebenen Empfehlungen für eine große Auswahl zur Verfügung stehender Front-End-Technologien gelten, könnte die Gestaltung von mobilen Web-Schnittstellen oder von mobilen Endgeräten, sog. „Smart Devices“, unter Umständen zusätzliche Richtlinien erfordern, die genauso wenig im Anwendungsbereich liegen wie weiter führende Hilfestellung bei der technischen Umsetzung oder zu Fragen der ästhetischen bzw. künstlerischen Gestaltung.

Ergonomie de l'interaction homme-système - Partie 151: Lignes directrices relatives aux interfaces utilisateurs Web (ISO 9241-151:2008)

L'ISO 9241-151:2008 fournit des lignes directrices relatives à la conception centrée sur l'utilisateur des interfaces logicielles utilisateurs pour les applications Internet (en abrégé, les interfaces utilisateurs Web), en vue d'augmenter leur utilisabilité. Les interfaces utilisateurs Web s'adressent soit à l'ensemble des utilisateurs de l'Internet, soit à des groupes restreints d'utilisateurs, tels que les membres d'une organisation, les clients et/ou les fournisseurs d'une société ou d'autres groupes spécifiques d'utilisateurs.
Les recommandations données dans l'ISO 9241-151:2008 se concentrent sur les aspects suivants de la conception des interfaces utilisateurs Web: les décisions de conception fonctionnelle et la stratégie de conception, la conception du contenu, la navigation et la recherche, et la présentation du contenu.
L'interface utilisateur des différents types d'agents utilisateurs, tels que les navigateurs Internet, ou d'autres outils, tels que les systèmes de développement de contenu Internet, n'entrent pas dans le domaine d'application de l'ISO 9241-151:2008 (bien que certaines lignes directrices puissent également s'appliquer à ces systèmes).
Les interfaces utilisateurs Web peuvent s'afficher sur un ordinateur personnel, sur un équipement portable ou sur tout autre dispositif connecté à un réseau. Bien que les recommandations fournies par l'ISO 9241-151:2008 s'appliquent à une gamme étendue de technologies existantes, la conception des interfaces Web mobiles ou des dispositifs intelligents peut nécessiter des lignes directrices supplémentaires et n'entre pas dans le domaine d'application de l'ISO 9241-151:2008, qui ne fournit pas, non plus, des recommandations détaillées sur la mise en œuvre technique ou sur les aspects relatifs à la conception artistique ou esthétique.

Ergonomija medsebojnega vpliva človek-sistem - 151. del: Smernice za oblikovanje uporabniških vmesnikov za svetovni splet (World Wide Web) (ISO 9241-151:2008)

General Information

• Status: Published
• Publication Date: 14-May-2008
• Withdrawal Date: 29-Nov-2008
• ICS: 13.180 - Ergonomics
• ICS: 35.240.99 - IT applications in other fields
• Technical Committee: CEN/TC 122 - Ergonomics
• Drafting Committee: CEN/TC 122/WG 5 - Ergonomics of human-computer interaction
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 15-May-2008
• Completion Date: 15-May-2008
• Ref Project: SIST EN ISO 9241-151:2008 - Ergonomics of human-system interaction - Part 151: Guidance on World Wide Web user interfaces (ISO 9241-151:2008)

Overview

EN ISO 9241-151:2008 (ISO 9241-151:2008) - "Ergonomics of human‑system interaction - Guidance on World Wide Web user interfaces" - provides human‑centred design guidance specifically for Web user interfaces with the aim of increasing web usability. It targets websites and web applications that address broad Internet audiences or closed user groups (e.g., organizational intranets, customer portals). The standard focuses on content and interaction design rather than low‑level technical implementation, browser internals, or aesthetic/artistic design.

Key topics and requirements

The standard emphasizes high‑level principles and practical guidance across four main areas:

• High‑level design decisions and strategy
  • Define user goals, target groups and context of use; adopt user‑centred design processes.
• Content design
  • Structure, clarity and relevance of content; organization for diverse user knowledge and tasks.
• Navigation and search
  • Consistent navigation, clear signposting, effective search functionality and support for wayfinding.
• Content presentation
  • Readability, layout and presentation techniques that support comprehension and efficient task completion.

Important scope notes (what it does not cover):

• User agents (e.g., browsers) and authoring tools are not the direct subject, though guidance may be applicable.
• Detailed technical implementation, mobile‑specific design or in‑depth aesthetic guidance are outside its scope.
• Accessibility is addressed conceptually, but comprehensive accessibility guidance is covered by related standards (see below).

Practical applications

ISO 9241-151 is practical for improving website and web application usability and for aligning design work with international ergonomic principles. Typical uses include:

• Developing or redesigning public websites, e‑commerce sites, intranets and web applications with a focus on usability.
• Creating content strategies, navigation schemes and search solutions that work for diverse user groups.
• Evaluating conformity of web UI designs to human‑centred usability practices during design reviews and usability testing.

Who should use this standard

• UX/UI designers and information architects
• Product managers and content strategists
• Front‑end developers (for design alignment)
• Accessibility specialists and compliance officers
• Usability researchers and QA teams

Related standards and guidance

• ISO 9241 family (notably ISO 9241‑11, ISO 9241‑110, ISO 9241‑171, ISO 9241‑20)
• ISO 13407 (user‑centred design process)
• ISO 14915 (multimedia/hypermedia design)
• W3C Web Accessibility Initiative (WAI) - practical web accessibility techniques

Keywords: ISO 9241-151, EN ISO 9241-151:2008, Web user interfaces, web usability, human‑centred design, navigation and search, content design, content presentation, web standards.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2008
(UJRQRPLMDPHGVHERMQHJDYSOLYDþORYHNVLVWHPGHO6PHUQLFH]D
REOLNRYDQMHXSRUDEQLãNLKYPHVQLNRY]DVYHWRYQLVSOHW:RUOG:LGH:HE,62

Ergonomics of human-system interaction - Part 151: Guidance on World Wide Web user
interfaces (ISO 9241-151:2008)
Ergonomie der Mensch-System-Interaktion - Teil 151: Leitlinien zur Gestaltung von
Benutzungsschnittstellen für das World Wide Web (ISO 9241-151:2008)
Ergonomie de l'interaction homme-système - Partie 151: Lignes directrices relatives aux
interfaces utilisateurs Web (ISO 9241-151:2008)
Ta slovenski standard je istoveten z: EN ISO 9241-151:2008
ICS:
13.180 Ergonomija Ergonomics
35.240.99 8SRUDEQLãNHUHãLWYH,7QD IT applications in other fields
GUXJLKSRGURþMLK
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 9241-151
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2008
ICS 13.180; 35.240.99
English Version
Ergonomics of human-system interaction - Part 151: Guidance
on World Wide Web user interfaces (ISO 9241-151:2008)
Ergonomie de l'interaction homme-système - Partie 151: Ergonomie der Mensch-System-Interaktion - Teil 151:
Lignes directrices relatives aux interfaces utilisateurs Web Leitlinien zur Gestaltung von Benutzungsschnittstellen für
(ISO 9241-151:2008) das World Wide Web (ISO 9241-151:2008)
This European Standard was approved by CEN on 8 May 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9241-151:2008: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 9241-151:2008) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of which is
held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2008, and conflicting national standards shall be withdrawn
at the latest by November 2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 9241-151:2008 has been approved by CEN as a EN ISO 9241-151:2008 without any
modification.
INTERNATIONAL ISO
STANDARD 9241-151
First edition
2008-05-15
Ergonomics of human-system
interaction —
Part 151:
Guidance on World Wide Web user
interfaces
Ergonomie de l'interaction homme-système —
Partie 151: Lignes directrices relatives aux interfaces utilisateurs Web

Reference number
ISO 9241-151:2008(E)
©
ISO 2008
ISO 9241-151:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
Contents Page
Foreword. iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Application . 6
5 A reference model for human-centred design of World Wide Web user interfaces . 7
6 High-level design decisions and design strategy . 8
7 Content design. 10
8 Navigation and search. 16
9 Content presentation. 26
10 General design aspects . 33
Annex A (informative) Overview of the ISO 9241 series. 36
Annex B (informative) Sample procedure for assessing applicability and conformance . 40
Bibliography . 49

ISO 9241-151:2008(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9241-151 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 4,
Ergonomics of human-system interaction.
ISO 9241 consists of the following parts, under the general title Ergonomic requirements for office work with
visual display terminals (VDTs):
⎯ Part 1: General introduction
⎯ Part 2: Guidance on task requirements
⎯ Part 3: Visual display requirements
⎯ Part 4: Keyboard requirements
⎯ Part 5: Workstation layout and postural requirements
⎯ Part 6: Guidance on the work environment
⎯ Part 7: Requirements for display with reflections
⎯ Part 8: Requirements for displayed colours
⎯ Part 9: Requirements for non-keyboard input devices
⎯ Part 11: Guidance on usability
⎯ Part 12: Presentation of information
⎯ Part 13: User guidance
⎯ Part 14: Menu dialogues
⎯ Part 15: Command dialogues
⎯ Part 16: Direct manipulation dialogues
⎯ Part 17: Form filling dialogues
iv © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
Guidance on software individualization is to form the subject of a future part 129.
ISO 9241 also consists of the following parts, under the general title Ergonomics of human-system interaction:
⎯ Part 20: Accessibility guidelines for information/communication technology (ICT) equipment and services
⎯ Part 110: Dialogue principles
⎯ Part 151: Guidance on World Wide Web user interfaces
⎯ Part 171: Guidance on software accessibility
⎯ Part 300: Introduction to electronic visual display requirements
⎯ Part 302: Terminology for electronic visual displays
⎯ Part 303: Requirements for electronic visual displays
⎯ Part 304: User performance test methods
⎯ Part 305: Optical laboratory test methods for electronic visual displays
⎯ Part 306: Field assessment methods for electronic visual displays
⎯ Part 307: Analysis and compliance test methods for electronic visual displays
⎯ Part 308: Surface-conduction electron-emitter displays (SED) [Technical Report]
⎯ Part 309: Organic light-emitting diode (OLED) displays [Technical Report]
⎯ Part 400: Principles and requirements for physical input devices
⎯ Part 410: Design criteria for physical input devices
⎯ Part 920: Guidance on tactile and haptic interactions
Framework for tactile and haptic interaction is to form the subject of a future part 910.
ISO 9241-151:2008(E)
Introduction
It is widely accepted that usability is a key factor in successful website design but until now there has been no
internationally agreed standard that specifically addressed the usability of World Wide Web (WWW or Web)
user interfaces.
World Wide Web user interfaces pose particular usability problems:
⎯ their users are diverse in knowledge, capabilities, language and other factors — for example, a World
Wide Web user interface that works well for subject-matter experts may be sub-optimal for ordinary users;
⎯ users’ goals vary considerably — for example, a site optimized for one set of tasks (such as e-commerce
transactions) could be sub-optimal for users whose tasks are different (such as information gathering);
⎯ different Web browsers or user agents often render Web content in different ways — for example, the
layout of individual pages can change, sometimes quite dramatically.
Users of the World Wide Web will have experienced the problems of inconsistency between websites and
often even within the same website. For example, something as straightforward as a link may be denoted by
underlining on one page, by a mouse-over on a second page and by nothing at all on a third page.
A number of guidelines for good practice exist, many on the Web itself, but these guidelines sometimes
conflict and can also be difficult to put into practice. While not addressing Web user interfaces specifically, a
number of International Standards are available that provide useful guidance on usability and the design of
user interfaces: ISO 9241-11 to ISO 9241-17 and ISO 9241-110 provide ergonomic guidance on the design of
software user interfaces in general, ISO 13407 on achieving usability by incorporating user-centred design
activities throughout the life cycle of interactive computer-based systems, and the ISO 14915 series of
standards on the design of multimedia and hypermedia aspects of user interfaces.
The recommendations and guidelines provided in this part of ISO 9241 apply primarily to the design of the
content of a website or, more generally, a Web application, the user's navigation and interaction, as well as
the presentation of the content. The user interface of different types of user agents (such as Web browsers) or
additional tools such as Web authoring tools are not the subject of this part of ISO 9241, although some
guidelines could apply to those systems as well. Aspects of the technical implementation of the
recommendations are also not within its scope.
An important objective for developing Web user interfaces is to make them accessible to the widest possible
range of users, including persons with disabilities. While some guidance provided in this part of ISO 9241 is
also important for the accessibility of Web user interfaces, it does not aim at covering accessibility in a
comprehensive manner. Common guidance on securing and improving accessibility to ICT (information and
communication technology) equipment, software and services can be found in ISO 9241-20, and detailed
guidance on the accessibility of software user interfaces in general can be found in ISO 9241-171, while the
World Wide Web Consortium's Web Accessibility Initiative provides guidance specifically for Web content,
user agents and authoring tools.
ISO 9241 was originally developed as a seventeen-part International Standard on the ergonomics
requirements for office work with visual display terminals. As part of the standards review process, a major
restructuring of ISO 9241 was agreed to broaden its scope, to incorporate other relevant standards and to
make it more usable. The general title of the revised ISO 9241, “Ergonomics of human-system interaction”,
reflects these changes and aligns the standard with the overall title and scope of Technical Committee
ISO/TC 159, SC 4. The revised multipart standard is structured as series of standards numbered in the
“hundreds”: the 100 series deals with software interfaces, the 200 series with human centred design, the
300 series with visual displays, the 400 series with physical input devices, and so on.
See Annex A for an overview of the entire ISO 9241 series.
vi © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 9241-151:2008(E)

Ergonomics of human-system interaction —
Part 151:
Guidance on World Wide Web user interfaces
1 Scope
This part of ISO 9241 provides guidance on the human-centred design of software Web user interfaces with
the aim of increasing usability. Web user interfaces address either all Internet users or closed user groups
such as the members of an organization, customers and/or suppliers of a company or other specific
communities of users.
The recommendations given in this part of ISO 9241 focus on the following aspects of the design of
Web user interfaces:
⎯ high-level design decisions and design strategy;
⎯ content design;
⎯ navigation and search;
⎯ content presentation.
The user interfaces of different types of user agents such as Web browsers or additional tools such as Web
authoring tools are not directly addressed in this part of ISO 9241 (although some of its guidance could apply
to these systems as well).
Web user interfaces are presented on a personal computer system, mobile system or some other type of
network-connected device. While the recommendations given in this part of ISO 9241 apply to a wide range of
available front-end technologies, the design of mobile Web interfaces or smart devices could require
additional guidance not within its scope; neither does it provide detailed guidance on technical implementation
nor on issues of aesthetic or artistic design.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 9241-11, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 11:
Guidance on usability
ISO 9241-12:1998, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 12:
Presentation of information
ISO 9241-13, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 13: User
guidance
ISO 9241-151:2008(E)
ISO 9241-14, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 14: Menu
dialogues
ISO 9241-15, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 15:
Command dialogues
ISO 9241-16, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 16: Direct
manipulation dialogues
ISO 9241-17, Ergonomic requirements for office work with visual display terminals (VDTs) — Part 17: Form
filling dialogues
ISO 9241-20, Ergonomics of human-system interaction — Part 20: Accessibility guidelines for
information/communication technology (ICT) equipment and services
ISO 9241-110, Ergonomics of human-system interaction — Part 110: Dialogue principles
ISO 9241-171, Ergonomics of human-system interaction — Part 171: Guidance on software accessibility
ISO 9241-303, Ergonomics of human-system interaction — Part 303: Requirements for electronic visual
displays
ISO 13407, Human-centred design processes for interactive systems
ISO 14915 (all parts), Software ergonomics for multimedia user interfaces
WCAG 1.0, Web Content Accessibility Guidelines 1.0, W3C Recommendation, World Wide Web Consortium
(W3C) (MIT, INRIA, Keio)
WCAG 2.0, Web Content Accessibility Guidelines 2.0, World Wide Web Consortium (W3C) (MIT, ERCIM,
1)
Keio)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
boolean search
search formulation using logical operators
3.2
browser
user agent allowing a person to retrieve and read hypertext, to view the contents of hypertext nodes (usually
Web pages), to navigate from one node to another, and to interact with the content
NOTE A browser also offers a set of operations, e.g. for navigating websites or for changing the visual appearance of
the content displayed.
3.3
conceptual content model
abstract model describing the concepts of an application domain, the relationships among those concepts and
the operations to be performed on the concepts or relationships

1) Working draft. Intended to supersede WCAG 1.0 in its final published version.
2 © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
3.4
content
web content
〈Web user interface〉 set of content objects
3.5
content object
interactive or non-interactive object containing information represented by text, image, video, sound or other
types of media
3.6
dynamic navigation link
computed link
link that is computed dynamically by the system based, for example, on the content of a database
3.7
frame
mechanism for dividing a browser window into independent windows, each displaying a different document, or
different parts of the same document
3.8
frameset
collection of frames and a corresponding layout structure that is presented in the same browser window
3.9
global navigation
set of navigation links available on all pages of a website
3.10
home page
start page
top page
main page through which users typically enter a website and whose URL is typically published or linked as the
main Web address of an organization or an individual
NOTE The term home page can be used differently in different contexts. Some groups will call a complete website a
home page.
3.11
interaction object
component of the Web user interface accepting user input
EXAMPLE Links, buttons, input fields, check boxes or selection lists.
3.12
Internet
worldwide interlinked computer systems and computer networks connected via gateways that enable the
transfer of data between them
3.13
intranet
computer network using Internet standards, the access to which is limited to members of a particular
organization such as a company
3.14
landmark page
landmark
main page in the navigation structure that can be directly accessed from many other pages
ISO 9241-151:2008(E)
3.15
link
hyperlink
〈World Wide Web〉 reference from some part of one document to (some part of) another document or another
part of the same document
NOTE Links are also called hyperlinks because hypertext and hypermedia systems make extensive use of this
concept. Links are used for activating navigation. They are represented, for instance, as element tags in the hypertext
markup language (HTML). The concept of links is also described in ISO 14915-2 in the context of multimedia user
interfaces.
3.16
link cue
textual or graphical presentation of a link showing information about the link target
3.17
media object
component of a Web document that is implemented by a single media type
EXAMPLE 1 A text object presenting a discussion about some topic.
EXAMPLE 2 An image object presenting a picture of some person.
EXAMPLE 3 A sound object presenting a song.
NOTE Adapted from ISO 14915-2:2003, definition 3.3.
3.18
navigation component
group of navigation elements placed together
3.19
profile
user profile
set of attributes used by the system that are unique to a specific user/user group
3.20
predefined user profile
profile based on a stereotype or combination of stereotypes
NOTE 1 Stereotypes used as the basis of a predefined user profile could include a role, a job function or a group
membership.
NOTE 2 Predefined user profiles are often used to define access privileges to specific Web content.
3.21
rendering
act whereby the information in a document is presented
NOTE This presentation is done in the form most appropriate to the environment (e.g. aurally, visually, in print).
3.22
navigation
Web navigation
〈World Wide Web〉 movement between or within Web pages or the movement within some presentation
segment presented on a page (e.g. the movement within a particular media object) that users perform to find a
specific function or piece of information
NOTE 1 In this part of ISO 9241, navigation is used as a convenient short form for Web navigation (see also
ISO 14915-2).
NOTE 2 Navigation steps are often initiated by activating some link.
4 © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
3.23
navigation structure
Web navigation structure
〈World Wide Web〉 structure composed of elementary or composite presentation segments (such as Web
pages or media objects contained in a page) and links, determining all possible paths on which users can
move around in a Web user interface
3.24
screen reader
assistive technology that allows users to operate software without needing to view the visual display
NOTE 1 Output of screen readers is typically text-to-speech or Braille.
NOTE 2 Screen readers rely on the availability of information from the operating system and applications.
3.25
site map
textual or graphical overview of the complete navigation structure of a website
3.26
splash screen
temporary page shown prior to the homepage when a website is first accessed
3.27
tool tip
small pop-up window that appears when the mouse pointer is moved over an interaction object and that
shows explanatory text or help information
3.28
transaction
action that involves inserting, updating or deleting information
3.29
Web user agent
user agent
front-end software that enables users to interact with a remote system through Internet protocols
NOTE A browser is a specific type of user agent.
3.30
uniform resource locator
URL
mechanism for identifying resources on the Internet (such as Web pages) by specifying the address of the
resource and the access protocol used
NOTE The official technical term as specified by the IETF is uniform resource identifier (URI), of which URL is a
subset.
3.31
Web page
coherent presentation of a content object or set of content objects and associated interaction objects through
a user agent
3.32
Web service
Web resource providing content and/or functionality that can be accessed remotely through standardized
protocols and software interfaces
ISO 9241-151:2008(E)
3.33
website
site
coherent collection of interlinked Web resources (for example, Web pages or Web services) that is located on
one or several computers connected to the Internet, and that can usually be accessed through the same
domain specification part of a URL
3.34
Web application
World Wide Web application
application providing functionality to the user through a browser or other type of user agent using Web formats
and protocols
NOTE Web applications in the sense of this part of ISO 9241 comprise websites that only deliver content, that
combine content delivery with application-specific functionality or that provide only specific application functionality such as
a particular Web service.
3.35
Web user interface
World Wide Web user interface
all aspects of a website or Web application related to content, functionality, navigation, interaction and
presentation that are relevant for using a website or Web application
3.36
within-page link
link leading to a target on the same page
4 Application
4.1 Intended user groups
The following groups are intended users of this part of ISO 9241:
⎯ developers and designers of Web user interfaces who will apply it during the development process;
⎯ content providers who generate and maintain the content of a website or application;
⎯ developers of content authoring tools who will integrate the mentioned recommendations into their
authoring tools;
⎯ usability evaluators who will check that Web user interfaces meet its recommendations;
⎯ buyers who wish to ensure the ergonomic quality of a software product or development.
4.2 Applying the recommendations
Each individual recommendation in this part of ISO 9241should be evaluated for its applicability and, if judged
to be applicable, should be implemented, unless there is evidence that to do so would cause deviation from
the design objectives or would result in an overall degradation in usability. In some cases, the designer may
need to trade off one principle or recommendation in favour of another to achieve an optimal design.
4.3 Conformance
If a claim of product or application conformity with this part of ISO 9241 is made, the procedure used in
establishing requirements for developing and/or evaluating World Wide Web user interfaces shall be specified.
The level of specification of the procedure is a matter of negotiation between the involved parties. Annex B
provides a basis both for determining and recording the applicability of all the recommendations and a means
for reporting that they have been followed. Other, equivalent, forms of reporting are acceptable.
6 © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
5 A reference model for human-centred design of World Wide Web user interfaces
The usability of a World Wide Web user interface is dependent upon many different but strongly related
factors. Giving structure to the complexity of Web user interface development, the reference model shown in
Figure 1 distinguishes between design, process and evaluation aspects. Addressing these three aspects in an
integrated manner is necessary to achieve human-centred Web user interface design. Since process and
evaluation aspects are covered in other International Standards, this part of ISO 9241 focuses on the design
aspects, with design guidance and recommendations.

Figure 1 — Reference model
In the reference model shown in Figure 1, Web user interface design is structured in five major areas or levels,
which have been used to structure this part of ISO 9241:
⎯ high-level design aspects;
⎯ conceptual content model;
⎯ content objects and functionality;
⎯ navigation and search;
⎯ content presentation.
ISO 9241-151:2008(E)
These areas can be seen as representing different levels in the overall design. While the levels do not imply a
particular sequence or process, higher-level issues should usually be addressed before lower-level design
decisions are made.
In addition, the following International Standards shall be consulted:
⎯ for guidance related to software user interfaces, ISO 9241-110, ISO 9241-11, ISO 9241-12, ISO 9241-13,
ISO 9241-14, ISO 9241-15, ISO 9241-16 and ISO 9241-17;
⎯ for guidance related to multimedia user interfaces, ISO 14915.
The other two parts of the model representing the process domain and the evaluation domain constitute
important additional aspects for the user-centred development of Web user interfaces. They are, however, not
elaborated in this part of ISO 9241.
The process domain represents the procedural aspects of developing Web user interfaces. The design of
Web user interfaces — as for the design of interactive software systems in general — should follow a
human-centred design process, including an appropriate analysis of the intended user groups and their tasks
or goals. ISO 13407 shall be consulted for guidance on human-centred design processes.
The evaluation domain refers to methods and criteria for assessing the usability of Web user interfaces. In
addition to perceptual and cognitive factors, emotional and belief-related issues such as the attractiveness or
trustworthiness of a website can be important when evaluating a Web user interface. Similarly, it can be
important to assess the organizational and social effects of an application. Specific evaluation criteria and
procedures will have to be specified for each of these different aspects, but are outside the scope of this part
of ISO 9241.
6 High-level design decisions and design strategy
6.1 General aspects
Websites take on an increasing variety of forms, ranging from conventional websites as collections of
interlinked Web pages to specialized Web services, possibly accessed through specific devices. Content
provision is frequently integrated with application functionality that is potentially delivered by a variety of
remote resources. These developments often blur the distinction between websites and conventional
applications, leading to the more general notion of Web applications. Web applications serve a wide spectrum
of purposes, such as, for example, public information websites, e-commerce applications, intranet applications,
location-adaptive services and many others. A clear definition of the purpose and strategic goal of the Web
application to be developed is therefore a critical high-level design decision that influences many other design
aspects.
Web applications and their context of use often have specific characteristics, which differentiate them from
conventional software applications. While conventional applications, for example, are frequently developed for
specific user groups, tasks or organizational contexts, public websites address a wide range of users with
different interests, information needs and tasks. Also, users are no longer bound to one specific system, but
may freely move to other websites with similar offerings.
In the process of designing a website, there are typically a large number of different stakeholders who
eventually will have to agree upon the purpose and design of the website. For this reason, issues such as
defining the target audience, selecting appropriate business models or the definition of a suitable genre and
design style for the site need to be explicitly stated and discussed among the stakeholders. When analysing
and defining the target user groups, it is critical to consider the diversity of the users expected and the range
of capabilities and disabilities they may have. An important design goal is to make Web user interfaces
accessible for the widest possible range of users, particularly taking into account potential user limitations in
perceiving, operating or understanding the Web user interface.
Depending on the purpose of a Web application, different design goals may be prioritized. For instance,
design goals such as “fun” or credibility may have different relevance for a banking website compared with an
8 © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
entertainment website. Prioritizing these goals with respect to the prospective users and their needs
constitutes an important aspect of designing a Web user interface.
6.2 Determining the purpose of a Web application
The purpose for which a Web application is developed should be explicitly defined in order to provide a clear
basis for developing appropriate content and functionality and for determining further design objectives.
NOTE Defining the purpose can involve, for example, developing the company image, promoting products or
supporting e-business. The purpose of a website could be narrowly defined as, for example, in an online ticket-sales
system, or more open-ended, a web site providing a platform for a community of users. Websites are often developed to
serve a number of different purposes at the same time. In such cases, aspects such as the ability of users to easily obtain
an overview of the scope of the content and functionality provided are important.
6.3 Analysing the target user groups
In the process of defining the purpose of a Web application, the target user groups should be identified.
NOTE General guidance on considering users and their tasks can be found in ISO 9241-2 and ISO 9241-11.
6.4 Analysing the users’ goals and tasks
The goals and tasks of the intended users should be analysed.
6.5 Matching application purpose and user goals
The purpose of the Web application (determined according to 6.2) should be compared and, if necessary,
matched with the users’ goals and tasks to ensure that users can accomplish their goals.
Frequently, there are conflicts between the goals of the provider of a website and user goals, for example, if
advertizing is one of the purposes of a website at the same time as users desire to use an information service
efficiently. In such cases, it is important to design the system so that the user is not negatively affected by the
goals of the provider.
6.6 Recognizing the purpose of a Web application
The intended purpose(s) of a Web application should be easily recognized by the user.
EXAMPLE 1 An online shopping website is recognizable by the title, description and graphical visual design of the
home page.
EXAMPLE 2 A short descriptive sentence (tagline) is used on an e-commerce website to convey what a company
does and how it differs from its competitors.
If a website has more than one purpose, it is important that the site's content and navigation support users to
discriminate among the purposes.
Web applications have over time evolved into different types, e.g. online news channels, electronic shops or
educational websites. These application types or genres often use specific, recurring forms and structures for
delivering content that may be tailored to different user groups. Employing these design patterns can be
valuable for making the purpose of a Web application easily identifiable and for providing consistent Web user
interfaces. However, it should also be noted that the boundaries between different genres are not well defined,
that they may overlap and that new genres can rapidly evolve due to the flexibility of the online medium.
6.7 Prioritizing different design goals
If there are different competing design goals they should be prioritized with respect to the most likely frequent
and/or critical tasks and needs of the users.
ISO 9241-151:2008(E)
Different design goals, such as, “present detailed information”, “design attractive pages” and “keep users
engaged” can conflict with one another. If that is the case, it is important that these design goals be prioritized
with respect to the user’s most frequent or critical tasks and to find suitable trade-offs.
6.8 ICT accessibility
ISO 9241-20 shall be consulted for guidance on ICT accessibility. Web user interfaces should meet its
requirements and recommendations.
6.9 Software accessibility
ISO 9241-171 shall be consulted for guidance on software accessibility. Web user interfaces should meet its
requirements and recommendations.
6.10 Web content accessibility
WCAG 1.0 and, superseding this, WCAG 2.0 when published in its final version, shall be consulted for
guidance on web content accessibility.
6.11 Identifying the website and its owner
The identity of a website and the website owner should be presented clearly and accurately and should be
displayed on all relevant pages. If the site owner is a business entity, appropriate information about the
company or organization should be provided.
EXAMPLE A corporate logo is available on all pages as a link to the home page where further information on the
website owner is presented.
NOTE 1 Identifying the website can include elements to both define and contact that organization, including business
name and contact channels that are open (address, e-mail, fax, phone, messenger, etc.).
NOTE 2 Adding suitable metadata is an additional means for making a website identifiable.
6.12 Coherent multi-site strategy
If the information or services provided by an organization or different parts of that organization are distributed
over different websites or subsites, a coherent strategy should be developed and implemented that allows
users to navigate consistently between the different sites and to locate relevant information or services without
prior knowledge of the purpose, interrelationship and content of the different sites.
NOTE A style guide might be of assistance to the user interface designer or developer in multi-site situations in
implementing a coherent strategy.
7 Content design
7.1 Conceptual content model
7.1.1 General
A conceptual model of the Web user interface describing the concepts and relations of the application domain
is an important basis for defining the content and the navigation structure. Such a conceptual model can be
developed by analysing the tasks and mental models of the prospective users, as well as existing information
structures such as subject hierarchies (taxonomies). Also, different user roles (e.g. consumer vs. business
customer) or expectations resulting from using other systems can influence the design of an appropriate
conceptual model.
10 © ISO 2008 – All rights reserved

ISO 9241-151:2008(E)
7.1.2 Designing the conceptual model
The conceptual model should be based on the tasks and mental models of the expected users or user groups,
using suitable task analysis techniques and taking into account the communication goals of other stakeholders
such as the information or service provider.
EXAMPLE In the conceptual model of an online shop, red wines from Bordeaux are a subcategory of red wines,
which are a subcategory of wine and so on. Due to the high popularity of Bordeaux wines, the category is shown at the top
level in the navigation structure to attract customers’ attention.
A conceptual model can be developed by a variety of methods such as card sorting or drawing affinity
diagrams and can be expressed, for example, in an information model using appropriate modelling techniques,
e.g. unified modelling language (UML) or topic maps.
Conceptual models can be conveyed through appropriate metaphors, for example, when using a newspaper
layout to indicate the importance of different articles.
7.1.3 Appropriateness of content for the target group and tasks
The content provided should be suitable for the purpose of the Web application, the target audience
(characterized by different goals, previous knowledge, preferences, etc.) and their tasks (see also
ISO 9241-11).
EXAMPLE The Internet presentation of a company provides an overview of the company’s competencies and
products relevant for prospective customers. The intranet of that company, however, focuses on the description and
support on internal processes and on the exchange of knowledge among the employees.
In order to provide appropriate content, a number of analysis and design techniques can be employed, such
as writing scenarios of the intended use, collecting and organizing topics in participative design sessions
involving prospective users, or developing information models with different degrees of formality (such as
thematic networks or class models).
7.1.4 Completeness of content
The content of a website should be sufficiently complete with respect to the purpose of the site and the typical
information needs of the user.
Users expect a website to contain all or most of the content relevant for their particular task and information
needs. For established types or genres of websites, such as the home pages of a computer supplier or travel
agency, presenting the range of topics and the level of detail typically associated with the genre are important
factors that contribute to the perceived completeness of the site.
Relevant content can also be provided by presenting links to other websites containing that content.
7.1.5 Structuring content appropriately
In order to achieve usable navigation structures, content should be structured based on the user’s tasks and
information needs as well as their mental model.
EXAMPLE In an online newspaper, bri
...