Subtitle processing

Subtitle data associated with a video including a number of subtitle elements (e.g. word or group of words) is received. A determination is made as to whether or not an element of the number of elements is to be displayed, and if so, the subtitle element is outputted for display. The determination may be based on a likelihood that an element (word) is known to a viewer, e.g. using a database. Additional information, e.g. semantic meaning, etymology, phonetic transcription, usage examples, can be displayed with the subtitle data. The element may also be translated, e.g. from a first to a second language, before the display determination is made. A viewer who has a little understanding of a language, but who is not fluent, may be spared the irritating display of more common words as subtitles, but may be assisted in understanding rarer or unfamiliar words.