Video typically has spoken information in the audio track and visual information in the video track. Any information that is only provided audibly or visually will not be accessible to people who can’t hear or see. Captions provide a text version of spoken words, along with any sounds that are important to understanding the content, so people who can’t hear can comprehend the information. People who can’t see get the information from the video through the audio track. Video that contains important information in the video track only requires additional content to convey the information to people who can't see.