The World Wide Web Consortium (W3C) established the main international standards and accessibility for the World Wide Web. The WCAG is created by the W3C to provide a standard for web content accessibility that can be shared around the world. The WCAG is meant to accompany organizations as a sort of blueprint on how to make their websites ADA compliant.

Reha opened the session by asking everyone to imagine they’re on a train platform, heading home from work, thinking about the great day they had and the presentation they knocked out of the park. They’re toying with their coffee cup, waiting for the train, when all of a sudden, a man walks up, puts a $5 bill in the cup, says “God bless,” and walks away.

...the full and equal enjoyment of the goods, services, facilities, or accommodations of any place of "public accommodation" by any person who owns, leases, or operates a place of public accommodation. Public accommodations include most places of lodging (such as inns and hotels), recreation, transportation, education, and dining, along with stores, care providers, and places of public displays.

It’s most outward feature is a font size and color contract toolbar that helps users more easily read your content. But it also does a lot of behind-the-scenes work like adding skip-to-content links, implementing an outline to the link :focus state for better keyboard navigation, utilizing longdesc for images and a whole lot more. Each feature can be turned on or off through a settings page.
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.
In many situations, covered entities communicate with someone other than the person who is receiving their goods or services. For example, school staff usually talk to a parent about a child’s progress; hospital staff often talk to a patient’s spouse, other relative, or friend about the patient’s condition or prognosis. The rules refer to such people as “companions” and require covered entities to provide effective communication for companions who have communication disabilities.
When choosing an aid or service, title II entities are required to give primary consideration to the choice of aid or service requested by the person who has a communication disability. The state or local government must honor the person’s choice, unless it can demonstrate that another equally effective means of communication is available, or that the use of the means chosen would result in a fundamental alteration or in an undue burden (see limitations below). If the choice expressed by the person with a disability would result in an undue burden or a fundamental alteration, the public entity still has an obligation to provide an alternative aid or service that provides effective communication if one is available.

The Federal Communications Commission (FCC) enforces regulations covering telecommunication services. Title IV of the ADA covers telephone and television access for people with hearing and speech disabilities. It requires telephone and Internet companies to provide a nationwide system of telecommunications relay services that allow people with hearing and speech disabilities to communicate over the telephone.