What is Web Accessibility?Article Updated May 1st, 2011
- Accessibility is a general term used to describe how easy it is for people to get to, use, and understand things. (Wikipedia)
It is a common mistake to believe that accessibility refers exclusively to the relationship between people with disabilities and their environment. That is, that making a building, website, or other device "accessible" is merely the process of ensuring that a person with a disability will be able to use it. This is not precisely wrong; it is merely incomplete.
Making a website accessible goes well beyond providing access to the most obvious market, which is users with visual disabilities. What I'm going to describe in this article are general descriptions of the areas where accessibility needs must be taken into consideration and a brief discussion of some of the techniques used to accomplish those needs.
Yes, one of the biggest barriers to the use of a website can be technology itself. If the entire world was using a single browser on one computer, then technology would cease to be an issue. However, this is very far from the case!
Although Internet Explorer is by far the most popular browser available, it has also historically been the least compliant with web standards. Other browsers together constitute up to 30% of web traffic. The actual proportions will vary widely for any given web site. Obviously, you don't want to alienate up to 30% of your potential visitors by providing an inferior experience! A critical element to start your web accessibility process is cross-browser testing. I routinely test in all currently active browsers with more than a marginalized share of the market.
Patience is a virtue. However, when the internet boasts billions of web pages - why would a visitor wait 5 minutes to see yours? The average visitor will usually wait little more than 8 seconds for an unknown website to load. Although the numbers relating to broadband connectivity are highly inconsistent, ranging anywhere from 35% to 75% of the population, even the higher-end numbers leave at least 25% of users reaching your web site with slower connections. Keeping the sizes of your web pages to a manageable level, using a minimal degree of multimedia and other high-bandwidth imagery is a key goal for universal accessibility. Some web sites inherently require greater multimedia resources, and that's entirely reasonable, but you should still avoid unnecessary consumption of bandwidth.
PDAs and Mobile Devices
The mobile internet is a huge segment of internet use. If your website is not accessible to mobile devices, you may be missing out on that potential traffic - and mobile browsers can have a whole host of complications. Mobile internet browsers have an infinitely variable degree of support for images, style sheets, and scripting. While the higher-end of mobile devices, such as Android devices or iPhones have browsers which are comparable to a desktop computer, other devices won't offer anything like that level of support. There are guidelines for best practice in mobile design which it's critical to follow for a successful mobile website.
Users with Disabilities
The range of disabilities which can be impacted by your web site design is tremendous. The most common category cited is blindness or low-vision, but in fact there's a huge range of potential issues in addition to those.
Blind users require the use of a screen reader to browse the internet. Screen readers function by reading the content of the web page to the user. Rather than merely reading the visual content, screen readers actually process the HTML code of the page. Because of this, your usage of appropriate semantic HTML makes all the difference for blind users. Using code right will help blind users to:
- Fill out web-based forms
- Navigate complex data tables
- Navigate within the text between various headers and sections of the page.
However, some common web design techniques, such as using tables for layout, can cause screen readers to become very confused about the correct order in which to read the page. The design can prove confusing and unusable to a blind user.
In addition to semantic HTML, a modicum of pure common sense web development can make the difference between an unusable, inaccessible web page and a sensible, easily-navigated site.
Partial or Low Vision
Particularly with the growing population of individuals over 50, issues with fading eyesight are becoming more and more important. Providing high enough contrast and a large enough font for the text to be readable is critical to providing a satisfying web experience for any user with vision problems. The text on a website should be resizable, and frequently it's a well-considered move to provide alternate views of the site with high contrast or very large text.
Careless choice of colors or a poor choice of instructions can render your website worthless to a color blind individual. Testing for inappropriate color choice and making certain that color is never the sole distinguishing factor between two items is necessary to provide an accessible site.
Keyboard or Alternate Device Navigation
Users with mobility problems including cerebral palsy, Parkinson's, quadriplegia or any of a wide variety of other physical disabilities may not be able to use a mouse. Websites should never require a mouse to perform any action. All links on a website should become highlighted clearly not only when the mouse hovers over them, but also if they've been selected using the tab key or other pointing device.
It is a common misperception that the deaf do not suffer problems when visiting web sites. They can see - so they should be able to read your text without any difficulty! In many cases this is true. However, some individuals who were born deaf can have difficult processing written text, and all deaf users will have a great deal of trouble with any audio or video with audio files. For any audio information, a transcription should always be provided. In addition, you should give some thought to providing customer support with the hard of hearing in mind.
Users with Learning Disabilities
Dyslexic users or users with autism may have difficulties processing certain types of information. Users with dyslexica may find text confusing, and be aided by clear graphical symbols associated with appropriate actions. Autistic individuals may have difficulties with idiomatic speech, metaphor, or other non-literal forms of speech.
Summary of Accessible Web Design
This article only provides a cursory examination of issues surrounding a fully accessible web design. Any section of this explanation could spawn an entire article of its own - and most of them have spawned several. For more reading:
Also by Joe Dolson:
- My Accessibility Articles at Practical eCommerce
- Color Blindness Myths and Misunderstandings
- Information on US Federal Section 508 Rules
- United States Disability Statistics
- Accessibility Issues for Learning Disabilities
- Accessible Design for the Deaf
- Best Practices: Writing for Accessibility
- Making Accessibility Happen
- Accessibility and Usability Issues with Ajax
- Accesskeys: Curse or Blessing
- Accessibility and Search Engine Optimization
Other valuable references:
- What is Web Accessibility? - Trenton Moss, A List Apart
- Dive Into Accessibility - Mark Pilgrim
- Evaluating Website Accessibility - Roger Johansson
- The Definition of Web Accessibility - WebAxe Accessibility Podcast (with myself as guest.)