Assistive technology refers to hardware or software that is used to assist the functional capabilities of people with disabilities, by reducing barriers and enhancing their everyday activities. Assistive technology for the Web includes an assortment of magnifier screens, a host of screen readers, closed caption equipment, a variety of keyboard enhancements, highlighting software and more. If a website is compliant in its coding the site's content is made accessible through these different assistive technology techniques.

Meeting the standards of an accessible Web site first requires an awareness of the special needs of users who have disabilities. The four main categories of disabilities are visual, hearing, mobility, and cognitive and learning disabilities.

Each person with a disability might encounter one or more barriers when trying to use the Web. Assistive technology can be used to minimize these barriers, however, if a website is not coded appropriately, the effectiveness of these technologies is limited.

Visual disabilities include blindness, low vision, color blindness, etc. People who are blind need text equivalents for the images used on the webpage because the assistive screen reader technology cannot obtain the information from the image itself. A person who has a visual disability will not find the mouse useful because it requires hand and eye coordination. Instead, this person must navigate the site using only the keyboard. For example, the tab and arrow keys help navigate around the page and the enter key works like a mouse click. A screen reader announces the item on the page that the user is focusing on.

Those who have low vision need the assistance of a hardware or software magnifier to enlarge the text beyond simple font enlargement. People who are colorblind or who have low vision benefit from good contrasting colors.

Magnification might reformat the location, change the contrast, or distort the size and fonts of the text and objects on the Web page. It is best to use multiple attributes. For example, if both color and a fill pattern are used on different bars on a graph, they can be viewed in either color or black and white. Instead of using size attributes on the font element to denote a heading, the heading element (<h1> tag) should be used to correctly mark up a heading so that assistive technology can identify headings.

Much of the web has adopted multi-media elements such as Flash™ for presenting information. People who are deaf or hard of hearing require visual representations of auditory information. Some solutions for these elements are closed captioning, blinking error messages, and transcripts of the spoken audio.

People with mobility disabilities have substantial limit of movement and difficulty in fine motor controls. Lifting, walking, and typing are either challenging or not possible. Mobility impaired individuals may find the keyboard, the mouse, or both difficult to use. Some need to find solutions to these problems with specialized input devices such as a head pointer, voice recognition, tong keyboard or a blow straw. Making a site accessible for these individuals would mean removing very precise mouse clicking, hierarchical pull down menus, and repetitive keyboard actions.

People with cognitive or learning disabilities, such as dyslexia and short-term memory deficit, need more general solutions, which include providing a consistent design and using simplified language. For example, by using a template, a Web developer can reuse the same layout and design for each page, so a person with a cognitive disability can more easily navigate through a website. People with cognitive or learning disabilities can also benefit from redundant input, such as providing both an audio file and a transcript of a video. By simultaneously viewing the text and hearing it read aloud, they can take advantage of both auditory and visual skills to better comprehend the material.

* Flash is a registered trademark of Macromedia Corporation.