Web Accessibility Jeffrey P. Bigham CSC 210, March 23, 2011 Achieving Web Accessibility and Usability

What is web accessibility?  the degree to which a web page or application is usable by people with different (and changing) abilities – visually-impaired people using screen readers – hearing-impaired people browsing w/out sound – physically impaired people (no mouse!) – color-blind people – cognitively-impaired people (simple language)

Scale of Access  37 Million Blind People in the World (125 million with low vision)  Increasing – Ageing Population – Situational Impairments  Access technology benefits 25% of web users 1 [1] “The Market for Accessible Technology. “ Forrester Research, 2003.

Web Potential for Blind People Web Advantages Convertible to Accessible Form Shop From Home Blind People Read 7x as Many Books The Law U.S. Government Requires Accessibility 1,2 NFB vs. Target Corporation 2 [1] Section 508 of the U.S. Rehabilitation Act. [2] Americans with Disabilities Act.

Provide Alt Text

Tables Confusing when used for layout - table heading element Takes the place of a element. Use tag to describe table.

Forms, Labels and Color  First Name

No Frames  is no longer valid HTML  confusing – esp when clicking on content in one frame causes an update in another  is ok, but should be avoided too

Javascript  barriers to navigation using keyboard – mousedown instead of click –  hidden content – content not functional or visible to AT – off-screen models, inaccessible APIs  lack of user control over content changes – selection boxes, auto-tabs  confusing – altering or disabling normal functionality

Dynamic Content  Two main problems with DHTML/AJAX – need to identify roles/states of scripted widgets – need to convey dynamically changing information – tatecheck.html tatecheck.html

Flash!  Like HTML/Javascript/CSS – Flash can be made accessible  Heavily dependent on user setup – right browser, OS, and AT combination  Avoid if possible!

Audio/Video mM Make your audio/video content accessible provide text alternatives

Usability  Accessibility is more than making access possible, it’s about making content usable for as many people as possible

X X X X h h h e b b START Keyboard Shortcuts

X X X X e b b START.heading { font-weight: bold; } Keyboard Shortcuts

Video!  oPI oPI

What is web accessibility?  the degree to which a web page or application is usable by people with different (and changing) abilities – visually-impaired people using screen readers – hearing-impaired people browsing w/out sound – physically impaired people (no mouse!) – color-blind people – cognitively-impaired people (simple language)

Accessibility Resources   