An affidavit is a written sworn statement of fact voluntarily made by an affiant or deponent under an oath or affirmation administered by a person authorized to do so by law. Such statement is witnessed as to the authenticity of the affiant's signature by a taker of oaths, such as a notary public or commissioner of oaths. The name is Medieval Latin for he/she has declared upon oath. An affidavit is a type of verified statement or showing, or in other words, it contains a verification, meaning it is under oath or penalty of perjury, and this serves as evidence to its veracity and is required for court proceedings.
See the article on the Nuremberg trials where the defense introduced hundreds of thousands of notarized affidavits. Revisionists argue that this enormous amount of testimonial evidence was almost completely ignored by the courts.