On February 20, 2014, the FCC unanimously approved the implementation of quality standards for closed captioning,addressing accuracy, timing, completeness, and placement (Wikipedia).

It started helping users to upload a script of the video with automated software that would match the text of the script to the applicable audio segments. Google also made few enhancements to the self-captioning facilities to make it improved. This innovative structure enabled captions to be automatedlyproduced by artificial intelligence. Before this crucial step was taken, YouTubers could only upload their own captions manually. In 2009, Google declared that the company was enabling automatic captioning capability to videos on the platform. Together with subtitles providing a textual alternative language translation of a videos’ primary audio language

They are commonly used as a transcription of the audio regarding avideo, occasionally including descriptions of non-speech elements. Captions represent additional or interpretive information.

Youtube captions