An interpreter is someone who helps two people to communicate when those two people do not speak the same language.
Interpreting is using spoken translation to convey a conversation between different languages. If you and the case officer in charge of your interview do not speak the same language, an interpreter will be present to relay what you said in your language to the officer.
The interpreter is not a participant in the conversation. The interpreter is only there to translate out loud what is said by you and the other participant in the same manner that it was said without omitting, adding or changing anything.
The interpreter is impartial and is subject to a duty of confidentiality.