Analysis and Changelog for Web Accessibility - Usability Document
- [Draft for Review] Web Accessibility and Usability Working Together
- [Editor's Draft](with internal notes) Web Accessibility and Usability Working Together
Page Contents
Version 1
Goals/purpose/objectives
- Encourage those working in usability, digital inclusion, etc. to coordinate with existing WAI guidelines, WAI, and the accessibility field.
- Clarify WAI's position that optimum accessibility is achieved with both standards and real people; and encourage accessibility specialists to do UCD.
Points to address:
- note that there times when differentiation is not necessary and times when it is.
- introduce the scope of accessibility. explain that it has aspects specific to people with disabilities (that are usually technical), and aspects that overlap with usability.
- introduce the scope of usability, specifically differentiating from accessibility, e.g., whereas accessibility has technical focus, usability practice is largely about process.
- explain the benefit of involving people with disabilities throughout design processes & including accessibility guidelines.
- address issues with "technical accessibility" versus usability - you should do UCD, which is including real people AND accessibility standards.
- emphasize the human aspect of accessibility and that it is about real people (as opposed to ticking-off checkboxes); and that developers need to learn the basics first in order to manage accessibility effectively.
- explain the role of technical standards for developing accessible products. explain the role of techniques to provide practical guidance for specific situations.
- promote coordination of related work with existing accessibility work, in particular by inviting contribution to WAI work by researchers. mention negatives of not building on existing work. differentiate broad issues of "inclusion", from accessibility for specifically people with disabilities.
Audience and Messages
Primary:
- Accessibility specialists (researchers, developers, etc.) - encourage them to use UCD techniques in addition to technical standards to improve both accessibility and general usability for all
- Usability researchers and practitioners - encourage them to include accessibility and people with disabilities throughout their work; let them know that WAI is open to working together and encourage them to work with WAI and existing WAI guidelines, techniques, and resources
- Anyone developing guidelines, policies, resources, etc that overlap with existing accessibility guidelines, policies, resources, etc -- e.g., for older users, einclusion, etc. - encourage them to coordinate with existing accessibility work, including WAI and WAI guidelines
Also:
- Policy people; procurement, purchasing, commissioning people - accessibility standards are essential; however, need to ensure they are implemented in a way that provides usable accessibility
- Usability specialists - you can use your existing UCD methodology and techniques to address a lot accessibility issues; people with disabilities highlight general usability issues
- Professors, teachers, instructors, students (particularly in human factors and usability) - do both usability and accessibility together
- People with disabilities, specialists, and advocates; people who are older, specialists, advocates - some usability issues don't belong in accessibility standards; sales point: when organizations ensuring usable accessibility, their website is more usable to all
Notes
- This doc is not defining accessibility, usability, user experience, etc. because such definitions are a matter of debate and are not necessary to meet the goals of this doc.
- Open issues:
- further addressing comments archives wai-eo-editors
- # Understanding Usability and User-Centered Design (UCD) Paragraph 1: Given that most readers will not have access to ISO 9241 documentation is it worth mentioning here? Is there a definitive overview we can link to if this stays?
- Title ideas:
- Web Accessibility and Usability: Coordinating Guidelines, Research, and Practice
- Web Accessibility, Usability, and Digital Inclusion: Coordinating Guidelines, Research, and Practice
- Coordinating Web Accessibility and Usability Guidelines, Research, and Practice
- Coordinating Web Guidelines, Research, and Practice with Accessibility
- Coordinating Web Usability Guidelines, Research, and Practice with Accessibility
- Working Together with Accessibility
- Benefits of Combining Web Usability and Accessibility
- Benefits of Usability for Accessibility
- [older ones from when the scope was different]:
- Combining Web Accessibility and Usability
- Interplay of Web Accessibility and Usability
- Web Accessibility and Usability Standards
- Relationship Between Web Accessibility and Usability
- Overlapping Relationship Between Web Accessibility and Usability
- Relationship Between Web Accessibility and Usability: Why it matters for research and web standards
- Accessibility for Inclusion
Accessibility and Inclusion
With Accessibility to Inclusion
With Accessibility to Full Inclusion
With Web Accessibility to Online Inclusion
With Accessibility to an Inclusive Web
Accessibility for an Inclusive Web
An Inclusive Web through Accessibility
For an Accessible and Inclusive Web
Achieving Inclusion with Accessibility
Global, Accessible, and Inclusive Web
- words, esp. translatability of:
"differentiating" between accessibility and usability <- probably easier to translate
"distinguishing" between accessibility and usability
other?
References & Resources
Internal References
- 30 Nov 2010 version, 29 Nov 2010 version
- 26 Nov 2010 EOWG minutes
- Nov 2010 comments to wai-eo-editors, and in survey
- 24 Nov 2010 version, 23 Nov 2010 version, 22 Nov 2010 version
- 12 Nov EOWG minutes
- 11 Nov 2010 version, 10 Nov 2010 version, 31 Oct 2010 version, 22 Oct 2010 version
- 22 Oct EOWG minutes
- 21 Oct 2010 version, 19 Oct 2010 version
- 15 October EOWG minutes
- 13 Oct 2010 version, 12 Oct 2010 version
- 08 October EOWG minutes
- 07 Oct 2010 version, 23 Sept 2010 version, 14 Sept 2010 version, 09 Sept 2010 version
- 11 June EOWG minutes
- 3 Nov 2009 EOWG minutes
- 31 Oct 2009 version
- 21 October 2009 WAI-AGE TF minutes
- 16 October 2009 EOWG minutes
- WAI-AGE Project Deliverables: The Overlapping Relationship Between Web Accessibility and Usability
Rationale: Much of the literature on older web users combines usability and accessibility issues. Usability and accessibility overlap and the line between them is not clear, particularly in the area of cognitive disabilities. Questions frequently arise with regard to what should be included in Web accessibility guidelines, versus what are general usability guidelines that should not be included in accessibility guidelines. A resource that addresses this issue directly would be valuable in discussion of covering the needs older users in accessibility guidelines. - W3C Web Accessibility Initiative Statement on Web Access Report from UK Disability Rights Commission
Related Resources
- Another –ability: Accessibility Primer for Usability Specialists, Shawn Lawton Henry, July 2002 - introduces the concept of "usable accessibility"
- "Understand the Relationship Between Accessibility and Usability" from "Understanding Web Accessibility", the first chapter of Web Accessibility: Web Standards and Regulatory Compliance, Shawn Lawton Henry, 2006
(An earlier version of the "Understanding Web Accessibility" (PDF) chapter from Constructing Accessible Web Sites (2002) book is also available online. See especially the first section "The Context of Accessibility: Usability".) - Is accessibility actually usability?, April 2009
- Accessibility and usability, Peter-Paul Koch, February 2004
- More Than a Set of Rules: consider Human and Social Factors Alongside Technical Guidelines, Glenda Watson Hyatt, 2005
- Accessibility in User-Centered Design: Background in Just Ask: Integrating Accessibility Throughout Design, Shawn Lawton Henry, February 2007
- "Distinguishing Between Accessibility and Usability Issues" in Just Ask: Integrating Accessibility Throughout Design, Shawn Lawton Henry, February 2007
- The relationship between accessibility and usability of websites, Helen Petrie and Omar Kheir, April 2007
- A Comparative: Accessibility and Usability, Mike Cherim, September 2007
- Usable Accessibility: Making Web Sites Work Well for People with Disabilities, Whitney Quesenbery, February 2009
- Usability or User Experience – what’s the Difference?, Tom Stewart, April 2008
- Is accessibility actually usability?, Alastair Campbell, April 2009
- Accessibility and Usability, Freedom Scientific - "It is entirely possible that a document or a Web page can be accessible and yet still be very cumbersome and sometimes nearly unusable. Documents and Web pages should be created not only with accessibility in mind, but with both accessibility and usability in synchronous harmony."
- Accessibility and Usability: Working Together at MIT (April 2012)
- Resource listings:
- Usable Accessibility - Usability in Civic Life, UPA
- Usable Accessibility, Shawn Lawton Henry
- Relationship Between Accessibility and Usability, Shawn Lawton Henry
- other resources?
- ISO
- ISO 9241-210 Human-centred design for interactive systems (redrafted from 13407)
- ISO 9241-20:2008 Accessibility guidelines for information/communication technology (ICT) equipment and services
- ISO 9241-171:2008 Guidance on software accessibility
- ISO 9241-151:2008 Guidance on World Wide Web user interfaces
- Articles linked from Usability Standards, including Three New Accessibility and Web Design Standards ISO 9241 Parts 20, 151 and 171, Tom Stewart, June 2009, and Exciting Times for Human Centred Design standards, Tom Stewart, May 2010
Changelog
- Early notes and changes are in the Archive section below.
- The References section above has links to previous drafts (many of which have changes tracked), meeting minutes, and e-mail comments.
- Changes after publication will be listed here.
Archive
This section contains notes from when the document scope was open and EOWG was exploring a wide range of issues. Version 1 was scoped as above.
Previous Analysis
Purpose, Goals, Objectives
Back round:
- Rationale: Much of the literature on older web users combines usability and accessibility issues. Usability and accessibility overlap and the line between them is not clear, particularly in the area of cognitive disabilities. Questions frequently arise with regard to what should be included in Web accessibility guidelines, versus what are general usability guidelines that should not be included in accessibility guidelines. A resource that addresses this issue directly would be valuable in discussion of covering the needs older users in accessibility guidelines.
- Proposal: Develop a resource which clarifies issues in the areas of accessibility and usability, with reference to the needs of older Web users.
Approach:
- Explain the scope of web accessibility
- Explain the scope of web usability
- Discuss the relationship between web accessibility and usability
- Discuss the role of the WAI Guidelines
- Discuss the relationship to other recommendations and how to ensure interoperability
Audience and Messages
Primary audience
- researchers doing studies on accessibility and usability -
- help them understand the scope of web accessibility standards, how they relate to general usability, and how to contribute techniques for usable web accessibility
- clarify the role of technical standards, training, and tools (in particular evaluation tools)
- clarify the role of browsers and other user agents in web accessibility
- explain the impacts of standards fragmentation on web accessibility
- people developing guidelines, standards, and policies for accessibility, older users, etc. - (same as above)
- policy people;
procurement, purchasing, commissioning people -- standards are necessary; however, need to ensure they are implemented in a way that provides usable accessibility
- professors, teachers, instructors, students -
- particularly people teaching/studying human factors/usability: here's info on how it's related to accessibility
Secondary audience
- web designers and developers -
- by ensuring usable accessibility, you make your site more usable to all (including people without disabilities)
- usability specialists -
- you can use your existing methodology and techniques to address much of accessibility
- accessibility highlights general usability issues
- people with disabilities, specialists, and advocates;
older users, specialists, and advocates -- understand that some usability issues might not be appropriate to cover in accessibility standards, for example requirements that relate connectivity, security, or general satisfaction with websites
- sales point: by ensuring usable accessibility, you make your site more usable to all (including people without disabilities)
Scenarios and Situations to Address
Scenario 1: Usability for Older People
Description: A researcher studies Web use by older people and deduces recommendations for web designers. These recommendations include general usability requirements (such as avoiding downloads, new windows, large pages, etc) as well as accessibility requirements (color contrast, readable text, etc).
Issue: The recommendations do not build on existing standards for accessibility (and usability), and contribute to fragmentation by confusing the web designers about which standards they can reliably follow. More over, the recommendations miss some of the web-specific background, such as "accessibility support", and are not applicable to a wide range of websites or situations.
Message: Explain that internationally harmonized web accessibility requirements are defined by WCAG, ATAG, and UAAG, and that contribution by researchers is welcome. In particular, to help develop techniques to meet accessibility requirements, and that reflect the observations made during the user studies.
Scenario 2: Usability for People with Disabilities
Description: A researcher studies Web use by people with disabilities and identifies usability issues on many websites that claim conformance to WCAG (usually WCAG 1.0) or that pass automated accessibility testing (using WCAG 1.0 tools). The researcher draws conclusions from these studies about the applicability of WCAG.
Issue: The conclusions do not take into account that the websites may not actually conform with WCAG. In particular, they probably do not conform with WCAG 2.0 which fixes many of the known issues that exist in WCAG 1.0 (including issues relating to ambiguity in interpretation). The conclusions propagate an unfortunate myth that there is something called "technically accessible" versus "really accessible".
Message: Explain that conformance with WCAG 2.0 ensures that websites are usable by people with disabilities (the level of conformance with WCAG 2.0 reflects the level of usability). Emphasize that contribution of new techniques, in particular "advisory techniques" that help optimize usability and "failure techniques" that help identify common mistakes made by developers, are welcome to help improve the guidance for developers.
Scenario 3a: Usability of Web Accessibility Standards (Researcher)
Description: A researcher studies development practices by web developers and identifies that the guidelines are often difficult to understand right away. In particular, starting out with the technical standards or with automated tools can lead to more confusion than without.
Issue: The researcher erroneously assumes that the guidelines are designed to provide the introductory basics for people who are new to web accessibility.
Message: Explain that technical standards and the tools that help check for compliance with such standards are not intended to be the starting point. Point to some of the existing resources (such as involving users, WCAG 2 at a Glance, and others), and explain that WAI is continually working to improve such resources.
Scenario 3b: Usability of Web Accessibility Standards (Developer)
Description: A developer identifies that the guidelines are often difficult to understand by the development team and decides to re-write the requirements in a way that is more understandable to them or that better applies to their specific organization.
Issue: The developer creates derivative work which includes addition, modification, or omission of web accessibility requirements, so that the internal requirements may conflict with the international standards.
Message: Explain that adding, changing, or omitting technical requirements can lead to fragmentation, which has a significant impact on web accessibility (link to standards harmonization). Point out some of the introductory resources (such as involving users, WCAG 2 at a Glance, and others) to help explain the guidelines for people new to web accessibility, and explain the role of techniques to optimize organization-specific development practices.
Scenario 4: Usability of Accessibility Features
Description: A researcher studies Web use by older people (or by people with disabilities) and identifies that assistive technologies and adaptive strategies are too complex or are not used due to other reasons. The researcher concludes that the dependencies between WCAG on UAAG are not being fulfilled and that website developers need to provide accessibility features (such as widgets to increase text size or change text colors) as part of the website.
Issue: The recommended solutions do not provide an incentive or increase pressure on user agent developers to improve the usability of their tools, in particular with regard to accessibility features. In fact, it puts the pressure on the web developer rather than to persuade user agent developers of the innovative potentials of better incorporating accessibility features.
Message: Explain that the recommended solutions have substantial limitations both for users and for web developers. For instance, settings made on one website can not be carried over to other websites (draw-back for users) and it is technically challenging to maintain the settings of a user for later visits to the same website (draw-back for web developers). Explain that teaching users how to make these settings in their own user agents (and point to better web browsing or similar) will be more effective and contributes to the recognition of accessibility features and their improvement over time.
Scenario 5: Usability for Diverse Audiences
Description: A researcher/developer identifies that different audiences sometimes need significantly different accessibility accommodation. For instance, some people need hierarchical navigation while others need topical navigation and some people need illustrative content while others need descriptive content to better use the Web. In some cases these needs can not be provided on the same web page but that multiple versions of the same content using different presentation/delivery modes may be needed.
Issue: The researcher/developer erroneously assumes that such solutions conflict with WCAG or other WAI guidelines, due to an unfortunate myth that conforming with WCAG means implementing a one-size-fits-all approach.
Message: Explain that adaptations, including adaptations that require multiple versions of the same content using different presentation/delivery modes do not conflict with WCAG as long as the system as a whole meets the accessibility requirements and the default presentation is accessible. Point out that WCAG requires multiple navigational structures, and that its definition of 'web page' includes dynamic and adapted content.
Questions and Myths to Consider
- Can a website meet accessibility standards and be technically accessible, but not be really usable by people with disabilities?
- Can a website be usable by people with disabilities, but not meet accessibility standards (not be "technically accessible")?
- When does such poor usability make a website not practically accessible by people with disabilities (even if "technically accessible")?
- How do general usability issues impact people with disabilities more than people without disabilities?
- Does designing a site for optimum "usable accessibility" compromise usability for people without disabilities?
- Do "usable accessibility" requirements conflict for people with different disabilities? (for example, website developer: "some people say my site has too many links/ too much information, but then they don't want me using javascript to create expanding menus for progressive disclosure") ("I used used XYZ fancy feature to put my 100s of links in a nice widget, but then people complained it's not accessible to screen readers. But then I put all the links in nested lists and people complained it's too much for people with cognitive disabilities.) Issue: The problem is not inherently accessibility, here, it's usability - you have too many links not well organized.
- What aspects of website accessibility and usability are web developers responsible for, versus browsers and assistive technologies. (for example, website developer: "If the browsers and AT don't do their job well, I shouldn't have to compensate for it, should I?") (for example: should websites have a text resize widget?)
[I think when we talk about accessibility/usability then we also need to briefly mention the context such as browsers and Web technologies. For instance, that HTML does not (yet) provide sections markup, so that the header elements have to be (mis-)used for that purpose. That is getting technical but messaging that "designers may need to compensate for the lack of usability in the browsers and technologies" is important.]
[@@it is about browsers not being usable and therefore website developers sometimes need to compensate for it. This is quite apparent for older people and others who are new to computer but not really an accessibility issue per se. If you are writing guidelines for developers making websites accessible, should they include compensations for browser and AT inadequacy?]
[Another complication when defining accessibility standards and guidelines is the responsibilities of the browsers and other components of web accessbilty.] - What if a feature that will improve usability for some users cannot be made accessible (e.g., an Ajax widget)?
Open Issues and change notes
- overall, how does this organization work - with some intro info and then answers to specific questions?
- issue with stating a myth/misunderstanding/illegitimate question put it in people's head... however, if don't people might miss it all together.
- ??? scope this down to differentiating between accessibility and usability in the context of web standards/guidelines
- if policy makers and procurement, etc. want to include usable accessibility, are we going to say anything specific about how they could? [see what 255 says & ISO & PAS78]
- "user experience" is more "modern" word - weave it in in addition to "usability"?
21 Oct 2009 (WAI-AGE teleconference discussion)
- consider weaving in WCAG 2 POUR
16 Oct 2009 (EOWG teleconference discussion)
- audience web developers & designers - helps argument to do accessibility, 'cause we're already doing usability
- consider coming up with examples to show the difference between accessibility and usability
- consider adding to the introduction that this is a subject that people can argue about till the cows come home
- "buy one, get one free" - if make it accessible, it will be usable for all
- FAQ - frequently ANSWERED questions
- look at mixing prose and FAQ
Old Notes
- ut with PWDs will find general usability issues
- Note that one reason usability not covered in technical accessibility specifications/guidelines mention is because of the legal aspect & association with disability discrimination law requirements (although is in US 255)
taken out of scope for version 1: main points: explain that WCAG 2.0 provides a solid framework along with flexibility, and for adaptability. optimizations to meet the need of specific audiences, including adaptability approaches, are part of accessibility; still, need to ensure accessibility for all. not about one size fits all, technical requirements give you options to make choices.
- ...
From Understanding Web Accessibility
The International Organization for Standardization (ISO) defines usability as the “extent to which a product can be used by specified users to achieve specified goals effectively, efficiently and with satisfaction in a specified context of use” [X]). Using this definition, accessibility focuses on:
- Including people with disabilities as “specified users”
- A wide range of situations, including assistive technologies, as the “specified context of use”
Put more simply, usability means designing your website to be effective, efficient, and satisfying. Accessibility makes sure it is effective, efficient, and satisfying for more people, especially people with disabilities, in more situations—including with assistive technologies.
Looking at definitions is easy. In practice, the relationship between accessibility and usability is more complex. For some people, it's a hotly debated topic. For most people, it's not an issue at all: When designing websites, it is rarely useful to differentiate between usability and accessibility.
However, there are times when the distinction between accessibility and usability is important, such as when looking at discrimination against people with disabilities and when defining specific accessibility standards. Yet the distinction is a common debate when defining accessibility standards such as WCAG. It is not clear what should be included in accessibility standards and what is purely usability and should not be included in accessibility standards.
One way to start looking at the distinction between the two is to categorize interface problems:
- Usability problems impact all users equally, regardless of ability; that is, a person with a disability is not disadvantaged to a greater extent by usability issues than a person without a disability.
- Accessibility problems decrease access to a website by people with disabilities. When a person with a disability is at a disadvantage relative to a person without a disability, it is an accessibility issue.
The distinction between usability and accessibility is especially difficult to define when considering cognitive and language disabilities. Many of the accessibility guidelines to improve accessibility for people with cognitive disabilities are the same as general usability guidelines. The distinction is further blurred by the fact that features for people with disabilities benefit people without disabilities because of situational limitations (that is, limitations from circumstance, environment, or device—such as using the Web on a mobile phone in bright sunlight with one hand because you're holding a sleeping baby with the other), and accessibility increases general usability.
Another point to cloud the distinction is “usable accessibility”—how usable are accessibility solutions. For example, if a site uses images for navigation and there's no alt text, the site is clearly not accessible. If the site has frustratingly verbose alt text (such as "This image is a line art drawing of a dark green magnifying glass. If you click on it. . .
"), one might say that the site is technically accessible because there is alt text; however, the alt text is so bad that the usability of the site is awful for anyone who relies on the alt text (which won't happen when you understand accessibility issues and include people with disabilities in your project).
There can be problems when people don't understand the issues around the distinction between usability and accessibility. For example, if a study reported that sites were not accessible but the problems were general usability issues (that impact all users, not just users with disabilities), the study could report incorrect conclusions about accessibility guidelines. Academic discussions of accessibility and usability can actually harm the cause of accessibility if they are not presented carefully for people who don't understand the complexity of the issue.
The bottom line on the issue of the relationship between accessibility and usability can be summarized as:
- Clearly, there is significant overlap between the two.
- The nuances of how they relate is of no consequence for most web development, which should have as its goal both accessibility and usability for all.
- In some specialized situations, such as legal policies, the distinction is important.
- It's a tricky issue; be careful what you do with it.
Using both UCD and WCAG as the basis for addressing accessibility ensures that the broad range of issues is covered well, at both the technical level and the user interaction level. You should be able to get most of what you need from WCAG. Involving users and using the UCD approach makes it easier and better.
From "Distinguishing Between Accessibility and Usability Issues"
There is not a clear distinction between accessibility for people with disabilities and general usability for all. Some things are clearly accessibility; some are clearly usability; and many things are in a gray area where accessibility and usability overlap.
One way to start looking at the distinction between the two is to categorize interface problems:
- Usability problems impact all users equally, regardless of ability; that is, a person with a disability is not disadvantaged to a greater extent by usability issues than a person without a disability.
- Accessibility problems decrease access to a product by people with disabilities. When a person with a disability is at a disadvantage relative to a person without a disability, it is an accessibility issue.
The distinction between usability and accessibility is especially difficult to define when considering cognitive and language disabilities. Many of the accessibility guidelines to improve accessibility for people with cognitive disabilities are the same as general usability guidelines. The distinction is further blurred by the fact that features for people with disabilities benefit people without disabilities because of situational limitations (that is, limitations from circumstance, environment, or device—such as using a mobile phone in bright sunlight with one hand because you're holding a sleeping baby with the other), and accessibility increases general usability.
Another point to cloud the distinction is “usable accessibility”—how usable are accessibility solutions. For example, if a website uses images for navigation and there's no alt text, the site is clearly not accessible. If the site has frustratingly verbose alt text (such as "This image is a line art drawing of a dark green magnifying glass. If you click on it, it will take you to the Search page for this Acme Company website" instead of just "Search"), one might say that the site is technically accessible because there is alt text; however, the alt text is so bad that the usability of the site is awful for anyone who relies on alt text.
Distinguish between usability and accessibility issues, as appropriate. When designing products, it's rarely useful to differentiate between usability and accessibility. However, there are times when such a distinction is important, such as when looking at discrimination against people with disabilities and when defining specific accessibility standards. In some usability test reporting it may be important to distinguish between accessibility and usability problems.
When usability test reports are used internally to improve the usability of the product for all users, it is usually not necessary to distinguish between usability and accessibility issues. However, when usability test reports make statements about accessibility, it can be vital to distinguish between usability and accessibility issues.
There can be problems when people don't understand the issues around the distinction between usability and accessibility.
A research study reported results on website accessibility without clearly separating general usability issues not related to accessibility. Because usability issues were mixed with accessibility issues, the study reported incorrect conclusions about web accessibility guidelines.
Academic discussions of accessibility and usability can actually harm the cause of accessibility if they are not presented carefully for people who don't understand the complexity of the issue.
From Accessibility in User-Centered Design: Background
What is Accessibility?
Accessibility basically means that people with disabilities can use a product. More specifically, accessibility is making user interfaces perceivable, operable, and understandable for people with a wide range of abilities. It encompasses all disabilities, or functional limitations, including visual, auditory, physical, speech, cognitive, and neurological disabilities. This includes temporary conditions, such as when you break your arm, or lose your glasses.
Accessibility also makes products more usable by people in a wide range of situations. Situational limitations come from circumstances, environments, and conditions, and can affect anybody—that is, people without disabilities as well. For example, situational limitations include using the Web on a mobile phone when your eyes are busy (such as driving), in bright sunlight, in a dark room, when your hands are full, in a quiet environment (where you don't want it to make noise), in a noisy environment (where you can't hear well), and in an emergency (when you may not be thinking clearly).
Thus, while access to people with disabilities is the primary focus of accessibility, it also benefits people without disabilities and organizations that develop accessible products because designing for functional limitations overlaps with designing for situational limitations.
For a more comprehensive introduction to web accessibility, including specific examples of how web accessibility benefits organizations and individuals, see the Understanding Web Accessibility book chapter.
Accessibility related to usability
Accessibility has a technical component and a user interface component. Accessibility of user interfaces can be approached through usability. International Organization for Standardization (ISO) 9241-11 defines usability as the "extent to which a product can be used by specified users to achieve specified goals effectively, efficiency and with satisfaction in a specified context of use." [2] Accessibility focuses on including people with disabilities as the "specified users" and a wide range of situations, including assistive technologies, as the "specified context of use".
Put more simply, usability means designing a user interface that is effective, efficient, and satisfying. Accessibility makes sure the user interface is designed to be effective, efficient, and satisfying for more people—especially people with disabilities, in more situations—including with assistive technologies.
Accessibility is about designing user interfaces so that more people can use your product effectively in more situations. [3]