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.
Examples of documentation that may be requested by the airline: Current documentation (not more than one year old) on letterhead from a licensed mental health professional stating (1) the passenger has a mental health-related disability listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM IV); (2) having the animal accompany the passenger is necessary to the passenger’s mental health or treatment; (3) the individual providing the assessment of the passenger is a licensed mental health professional and the passenger is under his or her professional care; and (4) the date and type of the mental health professional’s license and the state or other jurisdiction in which it was issued.16 This documentation may be required as a condition of permitting the animal to accompany the passenger in the cabin.
The contents of this booklet were developed by the Southwest ADA Center under a grant (#H133A110027) from the Department of Education’s National Institute on Disability and Rehabilitation Research (NIDRR). However, those contents do not necessarily represent the policy of the Department of Education and you should not assume endorsement by the Federal Government.

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.
Blind people, those with low vision, and people with other disabilities that affect their ability to read a computer display often use different technologies so they can access the information displayed on a webpage. Two commonly used technologies are screen readers and refreshable Braille displays. As discussed above, a screen reader is a computer program that speaks the text that appears on the computer display, beginning in the top-left corner. A refreshable Braille display is an electronic device that translates text into Braille characters that can be read by touch. These assistive technologies read text. They cannot translate images into speech or Braille, even if words appear in the images. For example, these technologies cannot interpret a photograph of a stop sign, even if the word “stop” appears in the image.
Many people with disabilities use a service animal in order to fully participate in everyday life. Dogs can be trained to perform many important tasks to assist people with disabilities, such as providing stability for a person who has difficulty walking, picking up items for a person who uses a wheelchair, preventing a child with autism from wandering away, or alerting a person who has hearing loss when someone is approaching from behind.
The ADA’s relationship with websites has been a complicated and often confusing story. The ADA does not explicitly address online compliance, even after undergoing several amendments in the far more web-oriented era of 2008. With no specific coverage under the law, it usually falls to the courts to determine how ADA standards apply to websites—or whether they do at all. 

Further complicating the issue, the U.S. recently appeared to be on the verge of adopting more comprehensive accessibility requirements. Federal regulations slated to go into effect in January 2018 would have held federal websites to the standards of WCAG 2.0 Level AA, the set of guidelines that provide the basis for online accessibility rules for most of Europe and many other nations around the world. The current administration, however, has withdrawn this requirement as part of a general push toward deregulation, leaving the online applications of the ADA as murky as ever.
ADA stands for the Americans with Disabilities Act, and it has been the law of the land since 1990. Title III (private sector businesses) of the Americans with Disabilities Act (ADA) prohibits discrimination on the basis of disability in places of public accommodation. It applies to any business that has 15 or more employees. While Title III of the ADA is typically known for its applicability to offline barriers such as lack of wheelchair access, acceptance of service animals, effective communication for hearing and vision impaired individuals, its focus in the digital age has turned to websites and online media.