Sign language interpreting is the use of a sign language to convey the information contained in the programme audio (speech and other important sounds) to viewers who are deaf and for whom sign language is their first language.
Sign languages use hand and finger shapes, movement, body language and facial expressions to convey meaning. Sign languages differ from country to country.
For example, Irish deaf people use Irish Sign Language, in India people use Indian Sign Language.
Different sign languages have their own unique grammar, semantics and vocabulary. Even within a country, there are often regional dialects and differences in some of the signs used by different cultural groups.
Some sign languages, such as British Sign Language (BSL), are languages in their own right with no direct mapping between the spoken language of the land and the local sign language.
Other sign languages are more closely related to the spoken language or are a direct visual representation of a spoken language.