Closed captioning is a technique used to display text on a television screen by request from the viewer. The “closed” is a reference to the fact that the captions must be “opened” or unlocked by the viewer, in contrast with open captions, which are always on display. Closed captioning is used most commonly by the deaf and hard of hearing, although anyone is welcome to use it. For instance, captioning can be useful when someone wants to watch television on a low volume setting without disturbing others, as it ensures that the viewer does not miss important dialog.
In some nations, there is a distinction between captions and subtitles. Captions record the speech on screen along with any notable information like sounds, while subtitles translate the speech on screen, assuming that the viewer does not understand what is being said. While both appear in the form of text on the screen, they have different functions. Some people call translations and transcriptions “subtitles,” which can be confusing for people who use “caption” for a transcription and “subtitle” for a translation.
Some nations require closed captioning by law so that deaf and hard of hearing viewers can access televised information. Closed captioning systems may consist of prepared transcripts which are displayed as needed, or of transcriptions produced instantaneously, usually with the use of computer equipment. Instant captions tend to be less reliable, and sometimes funny errors appear because the software has trouble understanding what is being said.
Closed captioning can be displayed in a number of ways. Scrolling captioning moves across the bottom of the screen with the dialog, sometimes in two layers so that people understand who is speaking. Pop-on captions flash onto the screen when someone talks, and then disappear, while paint-on captions appear letter by letter until the phrase is completed, and then disappear from the screen. You do not need a special television or video screen to receive closed captioning, as the captions are simply embedded into the video signal.
When something is broadcast in closed captioning, or when captioning is provided on a piece of recorded material, usually a small icon consisting of two C's inside a television-shaped box flashes on the screen at the beginning of the viewing session to indicate this. To activate this function, people can press a button or follow menu options, depending on what type of media they are viewing. Captioning will remain on until someone turns it off.