An Affidavit is a formal written statement of facts voluntarily made by an affiant under an oath or a public official such as the notary public or a person authorized to do so. It will be used to prove the truthfulness of a certain statement in court.
It is either the personal knowledge of the affiant or his/her information and belief or although not based on their personal perspective, the affiant states only what he/she feels they can state as true.