For the deaf and hard-of-hearing, subtitles are essential.
Blu-rays, DVDs and TV shows usually feature subtitling as an option, and it's also something that crops up on streaming media such as YouTube videos.
The Google-owned video site attempts to automatically add subtitles to videos, but the feature leaves a great deal to be desired.
You may have noticed this for yourself but if not, vlogger Rikki Poynter would like to bring it to your attention. Rikki, who is hard-of-hearing, complains that YouTube's subtitling is often "completely nonsensical". YouTube acknowledges that it has a long way to go.
Rikki is an active YouTube user and says that the automatic subtitling feature "makes absolutely no sense 99 per cent of the time". But the vlogger is not just complaining, she is campaigning to try to get things improved.
Talking to the BBC, she explains that because the automatic feature is so unreliable, more video uploaders should add subtitles manually.
The sheer volume of footage uploaded to the site every minute of every day means that YouTube has quite a task on its hands. But product manager Matthew Glotzbach says that the technology is just not quite good enough yet:
Rikki's campaign is gathering momentum and supporters in growing numbers, and YouTube says that investments are being made to make it easier for corrections to be made to subtitles that go awry.
Check out the video to see Rikki explaining more about what she hopes to achieve - and you can also find out how to add subtitles to your own videos: