Section 508 is an amendment to the Workforce Rehabilitation Act of 1973, signed into a law in 1998 by President Clinton. The amendment maintains that your website should be accessible to disable visitors. It is your responsibility to ensure that all the information available on your website is accessible to the general public, including people with disabilities.
Your 508-compliant website will increase your potential customer base. About 19%-20% of the present population has some form of disability and your 508-compliant website helps your organization from the branding point of view.
When the National Federation of the Blind (NFB) brought up the issue of disabled people not being able to access the websites of the federal agencies, the law was created. Section 508 lawsuits have been filed against major agencies and businesses, including the Small Business Administration, the Social Security Administration, and the US Department of Education. The National Association for the Deaf (NAD) also followed suite soon.
Hence, if you fall into the category of not-for-profit organizations, government businesses and agencies, public K-12 schools and higher education institutions and private business entities, 508-compliance is a must for you.