This means that the content of your site must be available to people with color-blindness, deafness, blindness, cognitive disabilities, and physical disabilities of all types. People using text-only browsers must have an equivalent experience to those using multimedia browsers. If you are a Federal Government entity or contractor, you'll need to consider these types of people as a part of your audience. The types of systems your audience will be using to access your site also need to be kept in mind. If you design a highway for Porsches, it won't meet the needs of folks driving Chevettes or Festivas.
Many older systems are unable to run the newest browsers or to utilize the newest technologies.
They are like those old clunkers, plodding along slowly in the right lane while the GTs and SUVs speed by them on the left, but using the highway nevertheless. Furthermore, many Internet surfers use neither PCs nor Macs, so you might want to avoid the use of platform specific technologies. Finally, one cannot overstate the importance of page download time, which varies according to the characteristics of the individual computer and the ISP, among other things. It is important to know which parts of your web site may be inaccessible to which people, and what the consequences of this inaccessibility will be. Furthermore, it is important to design a site that will be useable to the majority of folks you are trying to meet.