Disability is an evolving concept that can mean many things, including intellectual impairment, mental health problems, physical or sensory impairments, degenerative illnesses, mobility impairments, chronic illnesses, etc. Disability is often dynamic, and can change over the course of an individual’s life. Definitions of disability are constructed by medical diagnoses as well as society and culture. They can change over time, location, and environment, and their identification often depends on roles played by medical experts, institutions, and the legal system. Disabled people often experience exclusion, oppression, and inequality–a form of discrimination known as “ableism.” The media plays a role in shaping perceptions of disability and disabled people. See topic overview PDF for more.