Videos are great and they should be produced and delivered in ways that ensure that all members of your audience can access their content. Providing captions, audio descriptions and transcripts make your videos accessible to a wide audience,
Captions are text versions of the audio content, synchronized with the video.
Audio Descriptions are commentary and narration which guides the listener through the movie, tv show, theater or other art form with concise, objective descriptions of new scenes, settings, costumes, body language, and "sight gags," all slipped in between portions of dialogue or songs.
Still not totally sure what audio descriptions are and how they are different from captions? Play these 2 videos of the same trailer for movie Frozen to see the difference.
WebAIM’s mission is to expand the potential of the web for people with disabilities. They empower individuals and organizations to create accessible content by providing knowledge, technical skills, tools, organizational leadership strategies, and vision. Read their tips on Captions, Transcripts, and Audio Descriptions.