Audio description is an audio-narrated description of important visual elements of media like films, television programs, live performances, and tours to make them accessible to individuals who are blind or visually impaired. It describes elements like physical appearance, actions, body language, clothing, settings, and on-screen text through a narration that is inserted between portions of dialogue. Audio description provides crucial visual information that is missing for blind audiences by describing scenes, characters, and their movements to improve understanding and enjoyment of the described media.