According to WebAIM, captions are text versions of the spoken word presented within multimedia. Captions allow the content of web audio and video to be accessible to those who do not have access to audio. Though captioning is primarily intended for those who cannot hear the audio, it has also been found to help those that can hear audio content, those who may not be fluent in the language in which the audio is presented, and those for whom the language spoken is not their primary language. Captioning can also benefit anyone in a noisy environment or an environment that requires silence.

Common web accessibility guidelines indicate that captions should be:
  • Synchronized—the text content should appear at approximately the same time that audio would be available
  • Equivalent—content provided in captions should be equivalent to that of the spoken word
  • Accessible—caption content should be readily accessible and available to those who need it

On the web, synchronized, equivalent captions should be provided any time multimedia content (generally meaning both visual and audio content) is present. This guideline obviously pertains to the use of audio and video played through multimedia players and HTML5 video, but can also pertain to technologies such as Flash or Java when audio content is a part of a multimedia presentation. 

Captions can be either closed (turned on or off) or open (always visible). One of the easiest tools for creating captions for videos is InqScribe. Featuring a simple split-pane interface, InqScribe displays video in the left pane and transcript entry with timestamp insertion in the right pane.

InqScribe split-pane interface

sample video being played in inqscribe with the transcript and timing on the right

Video with closed captions displaying
sample closed captioning being played on a video

Caption content provided by WebAim: Copyright © 1999-2020 WebAIM (Web Accessibility in Mind). All rights reserved.

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