The Americans with Disabilities Act (ADA) was first passed in 1990. Twenty years later, the US Department of Justice released an update called the 2010 ADA Standards for Accessible Design. These standards cover the design of physical spaces and have been interpreted to include web locations as well, so it can be difficult for the would-be accessible website designer to use them.
As I mentioned above, under each WCAG 2.1 principle is a list of guidelines, and under each guideline are compliance standards, with techniques and failure examples at each level. Some guidelines include only Level A items; others include items for multiple levels of conformance, building from A to AAA. At each stage, you can easily see what more you would need to do to reach Level AA or AAA. In this way, many websites include elements at multiple levels of accessibility.
Businesses and nonprofits: in determining whether a particular aid or service would result in an undue burden, a title III entity should take into consideration the nature and cost of the aid or service relative to their size, overall financial resources, and overall expenses. In general, a business or nonprofit with greater resources is expected to do more to ensure effective communication than one with fewer resources. If the entity has a parent company, the administrative and financial relationship, as well as the size, resources, and expenses of the parent company, would also be considered.
Federal law isn't the only consideration for businesses. Additionally, each state interprets the law differently. Consider the case against Netflix in 2012. Lawsuits were brought in federal court in Massachusetts and California. Netflix was accused of violating the ADA by not offering "closed captioning" options for its Internet streamed movies. Illustrating the complexity of this issue, the courts reached completely opposite decisions. Massachusetts held that Netflix must comply with the ADA, while the California court found that Netflix did not fall under the ADA's definition of "public accommodation."
While legal considerations might be your biggest worry, making your site more accessible is simply good customer service. More than 39 million Americans are blind and another 246 million have "low vision," Another one million are deaf in the U.S. Add to that people with mobility issues that prevent them from using their hands and that's a huge portion of the country's buying power.
Input Assistance: When users are entering input into the website, any input errors are automatically detected and written out, providing, for instance, text descriptions that identify fields that were not filled out or data that was in the wrong format. The website also provides suggestions to fix the errors. Input fields and buttons are labeled to provide their functions and instructions. If the user’s input is being used for legal purposes or financial transactions, then the user must be able to reverse submissions or correct errors.
Title III of the Americans with Disabilities Act (ADA) requires that businesses and nonprofit services providers make accessibility accommodations to enable the disabled public to access the same services as clients who are not disabled. This includes electronic media and web sites. While the ADA applies to businesses with 15 or more employees, even smaller businesses can benefit from ensuring that their websites are ADA compliant. Doing so opens your company up to more potential clients and limits liability. Web developers should include ADA compliant features in the original site and application plans.