The ADA is the Americans with Disabilities Act, passed almost 30 years ago in 1990. This act was originally put in motion pertaining solely to physical location. It requires establishments to provide people with disabilities easy access to various levels throughout the business. This act was set to achieve an equal experience to all people, handicapped or not.
HTML tags – specific instructions understood by a web browser or screen reader. One type of HTML tag, called an “alt” tag (short for “alternative text”), is used to provide brief text descriptions of images that screen readers can understand and speak. Another type of HTML tag, called a “longdesc” tag (short for “long description”), is used to provide long text descriptions that can be spoken by screen readers.
If you have a disability and are qualified to do a job, the ADA protects you from job discrimination on the basis of your disability. Under the ADA, you have a disability if you have a physical or mental impairment that substantially limits a major life activity. The ADA also protects you if you have a history of such a disability, or if an employer believes that you have such a disability, even if you don't.
The ADA itself holds different organizations to more/less stringent standards based on a host of factors, government funding being a major one. Government agencies themselves are usually held to the most severe standards. That said, while ADA has adopted WCAG as the defacto standard, from what I’ve seen it appears they’re going with AA compliance as the most reliable one. That said, we’ve done work with some organizations who’ve chosen to comply with AAA in an effort to be as buttoned up as possible from an accessibility and experiential perspective. We’ve also worked with some who have tighter budgers and aim for level A compliance and have a more “react and repair” mindset when they discover anything in their site that is giving someone hardship from an accessibilirt standpoint.
The Department has assembled an official online version of the 2010 Standards to bring together the information in one easy-to-access location.  It provides the scoping and technical requirements for new construction and alterations resulting from the adoption of revised 2010 Standards in the final rules for Title II (28 CFR part 35) and Title III (28 CFR part 36).
The Department of Justice (DOJ) has specifically stated in rulings that websites should be designed so they are accessible to individuals who have vision, hearing, and physical disabilities. There’s a growing body of case law where the DOJ required companies to provide an ADA compliant website and levied hefty penalties when sites failed to measure up.
This is the reason why I think web design firms have to position themselves as solution providers and not just web guys/gals. A client doesn't need a website, they need sales. The website is just part of that solution but it's not the solution and unlike web design, service like email marketing automation, SEO, and PPC requires an experienced professional.
WEB DESIGN: For over twenty years, I have developed client sites for large and small businesses and in every sector imaginable. I develop responsive websites with WordPress which is the industry standard for website development. I specialize in Responsive Web Design so your website displays automatically on any device. Responsive design makes the most sense when developing your new business website because the design adjusts itself to the size of a user's screen. Your website visitors will be able to view all of your content on a desktop computer,...
Navigable: Content that’s repeated on multiple pages can be easily skipped. All pages have informative titles, headings, and labels that describe the page’s content and hierarchy. Navigating the page must take place sequentially, in a meaningful order that preserves relationships on the page. All link text is descriptive in order to make clear where the link will take users. If users are navigating via a keyboard, the current focus of the keyboard is always highlighted and visible.
ADA website compliance is about making sure that everyone has equal access to all the elements on your website and apps. That may mean you need to provide alternatives for some of the functions and content on your site in order to meet ADA website compliance standards. Here’s a quick rundown of some of the accommodations that need to be incorporated into your website to meet the ADA guidelines:

Once you have been hired and started work, your employer cannot require that you take a medical examination or ask questions about your disability unless they are related to your job and necessary for the conduct of your employer's business. Your employer may conduct voluntary medical examinations that are part of an employee health program, and may provide medical information required by State workers' compensation laws to the agencies that administer such laws.