The three terms get used interchangeably, but they solve different problems. Here's what each one is, when to use it, and why it matters for reach and compliance.
In this article
Subtitles, closed captions and SDH all put text on screen, but they exist for different reasons — translation, accessibility and platform compliance. Getting the right one avoids both legal risk and lost audience. Here's the plain-English version.
Subtitles
Subtitles assume the viewer can hear the audio and focus on the words being spoken — usually to translate dialogue into another language, or to transcribe it for clarity. They don't describe non-speech sounds. They're the right choice for reaching audiences in other languages. See our subtitling services, including YouTube subtitling.
Closed captions
Captions are designed for viewers who can't hear the audio, so alongside the dialogue they mark speaker changes and important sounds (“[phone rings]”). “Closed” means the viewer can switch them on or off. They're central to accessibility and to sound-off social viewing. Explore our closed captioning services.
SDH (Subtitles for the Deaf and Hard of Hearing)
SDH blends the two: the accessibility detail of captions with the styling and file formats of subtitles. It's the standard on streaming platforms and physical media, and is often required when delivering to broadcasters and studios. Learn more about SDH subtitling.
Quick comparison
| Format | Primary purpose | Includes sounds / speaker IDs? |
|---|---|---|
| Subtitles | Translate or transcribe dialogue | No |
| Closed captions | Accessibility for deaf / hard-of-hearing viewers | Yes |
| SDH | Accessibility in subtitle styling / streaming formats | Yes |
Which do you need?
Reaching other-language audiences? Subtitles. Meeting accessibility requirements or optimising for muted social feeds? Captions or SDH — SDH specifically when a platform or broadcaster asks for it. Many projects use more than one. Whichever you pick, make sure they're readable — our subtitle reading speed checker tells you if a line stays on screen long enough. If you also need the video voiced in another language, see our voice over translation service, or tell us about your project and we'll recommend the right mix.