What are Captions?
Captions (sometimes called “subtitles”) are the textual representation of a video’s soundtrack. They are critical for viewers who are deaf or hard of hearing, and they are also a great tool for improving the reading and listening skills of others.
If you upload video to the Web, and that video includes sound, you should always include a text alternative, such as captions. As an added bonus, since most captioning for the Web relies on text, providing captions for your videos will ensure that they are indexed by search engines more quickly and accurately, meaning your video will reach more people.