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 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.

• To obtain a declaration on a legal document, such as an application for voter registration, that the information provided by the applicant is truthful to the best of the applicant's knowledge. If, after signing such a declaration, the information is found to be deliberately untrue with the intent to deceive, the applicant may face perjury charges.