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Most common pitfalls regarding accessibility

  1. Non-Text Elements -Text is the “information format” that can be most easily translated by computers. 
  2. Tables and Forms - All information on a page should make sense when “linearized” (by reading the content in the order it appears in the code
  3. Image Maps & Navigation - Users should be able to navigate without the use of a mouse (e.g. with the keyboard). 
  4. Color - Information conveyed using color should be represented with text as well for visually impaired users or text-only browsers. 
  5. Text and Paragraph Formatting - Webpages should not rely exclusively on style-sheets, JavaScript, images, plug-ins, etc. to display information.


What is accessibility?

Accessibility, with respect to the online world, refers in general to how barrier free the technology is.  We will look specifically (although not exclusively) at accessibility as it relates to users with disabilities.  With a particular population mind, we can develop a more precise definition by looking at what defines accessibility problems: Accessibility problems are those that make it more difficult for persons with disabilities to use an application or service than for a non-disabled person.

The Internet is often called the Information Superhighway, and just like a highway that cars drive on, the Internet is prone to pitfalls.  For instance, when there are too many vehicles on a given stretch of road, traffic jams occur.  Similarly, when too many people are trying to access a network, the network can become slow.  Using the same highway analogy, accessibility refers to the condition of the road.  Is it paved?  Are there potholes?  Does it flood when it rains?  Are there low bridges?  Online, accessibility deals with such things as providing text equivalents for images, page elements that can be accessed with the keyboard or alternate pointing device, captioned audio, and associating data table cells with header cells. 

Accessibility vs. Usability

While accessibility and usability often go hand in hand, there is a distinction between them.  Whereas accessibility refers to how barrier free something is, usability focuses on how intuitive and easy the technology is for all people to use.  In keeping with the highway analogy, if accessibility is the condition of the road, then usability is how well the road can be navigated.  Are there too many four-leaf clovers?  Are the exits numbered sequentially?  How would an additional lane affect traffic flow?  Is a 6-way intersection really a good idea?  For a Web site, usability means such things as clarity of content, ease of navigation, and logical organization of pages.  As mentioned above, accessibility means things like text equivalents for graphics and audio, and properly formatted tables.  Accessibility aims to make the Web site open to a wider user population, while usability aims to make the target population of the Web site happier, more efficient, and more effective.

Accessibility vs. Diversity

This discussion of accessibility does not address issues of cultural diversity such as language differences or cultural preferences and traditions. For the purpose of this report, accessibility refers specifically to the ability of individuals with a disability to use a Web site.  Language translation is not considered for several reasons.  Primarily, accessibility deals with removing barriers to the contents of a Web page, whereas translation means duplicating and reformatting the contents.  It is analogous to the difference between making highway lanes wide enough for larger vehicles and creating a separate highway for those who drive on the left side of the road.

Content, Structure, and Presentation

Generally, an information technology system is accessible to people with disabilities if it can be used in a variety of ways that do not depend on a single sense or ability.  In order to do this, it is important to be able to distinguish between the content, structure, and presentation of a Web page. 

Content - What is said, the information to be communicated.  It can be textual or graphical.  If your page had "pure" content, all it would contain would be line after line of text and graphics.

Structure - How the page is organized/ordered.  Chunking information into paragraphs or sections helps organize information logically.  Emphasizing headings with large or different fonts helps the reader quickly locate the main ideas on the page.

Presentation - How the page appears, feels, and sounds.  Elements such as fonts and text size, tables used for layout, invisible GIFs, and style sheets control the "look and feel" of the page. 


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