Web Accessibility insures that everyone can view the contents of your web site and appreciate the entire experience. What at first seems simple and easy becomes more complex when you consider the various ways that content can be displayed, viewed and transmitted.
The solving of these issues is what accessibility is all about.
Any number of laws and statues exist that govern accessibility in the United States (Section 508) and worldwide. Much of this legislation not only concerns online accessibility but also accessibility in many areas of life.
Section 508 governs accessibility in the US. It allows all individuals including those with disabilities access to information technology: including text-only pages (helping people with visual disabilities) and usability for people that are visually impaired such as alternative keyboard navigation.
This also assures accessibility to your web page graphics using assistive technology such as screen readers and refreshable Braille displays (this is accomplished by using text labels and descriptors for graphics).
An accessible web means individuals with disabilities can actively participate like the rest of us.