Interpreters can work on a freelance basis or for an international organisation, for example. There are various types of interpreting, which involve different settings, equipment, and can require distinct types of training.
Either simultaneous or consecutive. In simultaneous interpreters often work in a booth, for example at conferences or at meetings for international organisations (EU, NATO, UN). In consecutive interpreters perform to an audience, for example at conference plenary discussions and after dinner speeches. Usually speeches will last several minutes, and the interpreter will take notes before giving them back in the target language.
Public service interpreting
Interpreters work in the local community, for instance at Court, at police stations, in hospitals or airports. (They therefore help provide access to such services for individuals who would otherwise be excluded from them due to language barriers.)
Diplomatic and business interpreting
Typically consecutive interpreting. This includes liaison, or dialogue interpreting, where an interpreter works in both directions between two parties to facilitate a discussion, and whispering (often called by its French term, ‘chuchotage’), where interpretation is whispered to a small number of listeners.
Sign language interpreting
Sign language (e.g. British Sign Language, or BSL) interpreting is not a separate category from those above, but might be used in any of them. A BSL interpreter could work in a range of settings (since the introduction of the Disability Discrimination Act Deaf people are entitled to access any service available to the general public, including social events, theatre, television programmes, etc., and it is estimated that to meet demand we need ten times the number of qualified interpreters now available).