The law defines disability according to the Americans with Disabilities Act (ADA) and the subsequent Americans with Disabilities Amendments Act of 2008. The ADA is a civil rights law that prohibits discrimination and guarantees that people with disabilities have the same opportunities as everyone else to participate in the mainstream of American life. According to the ADA, disability is defined as "any individual who has a physical or mental impairment that substantially limits one or more of the major life activities of such individual, has a record of such an impairment, or is regarded as having such an impairment."
To be considered a person with a disability, and a member of this protected class, you must first meet a legal standard referred to as "qualified." In the workforce, a "qualified person with a disability" basically means you have the requisite skills for the job to which you are applying (or currently hold) with or without a reasonable accommodation. A reasonable accommodation is a modification or adjustment that will help you to succeed. In postsecondary education, a "qualified person with a disability" means you meet the academic standards for admission or participation with or without a reasonable accommodation.
 A "physical or mental impairment" includes "any mental or psychological disorder, such as an intellectual disability, organic brain syndrome, emotional or mental illness, and specific learning disabilities."
 Major life activities are those functions that are important to most people's daily lives. Examples of major life activities are breathing, walking, talking, hearing, seeing, sleeping, caring for one's self, performing manual tasks, and working.
 "Regarded as" means that the person either: (a) has an impairment that does not substantially limit a major life activity; (b) has an impairment that substantially limits a major life activity only as a result of the attitudes of others toward them; or (c) does not have any impairment, but is treated by an entity as having an impairment.