Visible movements of hands, body and face that replace the vocal elements of a spoken language is called sign language. Depending on personal preferences, people who have hearing loss or are deaf in the US who use sign language might communicate using the unique grammar of American Sign Language (ASL) or some variety of signing that uses features taken from both ASL and English Sign Language. However there is a problem that not all people understand sign language. Therefore sign language interpreter is required. An interpreter is a person who is a mediocre between two people who don’t understand each other, who speak different languages. Therefore an interpreter in sign language is a person who is not def but knows sign language and interprets what is being said.They are often used to enhance the interpretation between def and hearing people. A person, in order to be this kind of interpreter needs to undergo a lot of training since sign language is a language for itself with its own syntax.
The interpretation flow is normally between a sign language and a spoken language that are customarily used in the same country, such as French Sign Language (LSF) to spoken French in France, Spanish Sign Language(LSE) to spoken Spanish in Spain, British Sign Language (BSL) to spoken English in the U.K., and American Sign Language (ASL) to spoken English in the USA and most of anglophone Canada (since BSL and ASL are distinct sign languages both used in English-speaking countries), etc. Sign language interpreters who can translate between signed and spoken languages that are not normally paired (such as between LSE and English), are also available, albeit less frequently.