Language interpretation is the facilitating of oral or sign-language communication, either simultaneously or consecutively, between users of different languages. The process is described by both the words interpreting and interpretation.

In professional parlance, interpreting denotes the facilitating of communication from one language form into its equivalent, or approximate equivalent, in another language form; while interpretation denotes the actual product of this work, that is, the message thus rendered into speech, sign language, writing, non-manual signals, or other language form. This important distinction is observed in order to avoid confusion.

An interpreter is a person who converts a thought or expression in a source language into an expression with a comparable meaning in a target language in "real time". The interpreter's function is to convey every semantic element (tone and register) and every intention and feeling of the message that the source-language speaker is directing to target-language recipients.