A gap affidavit is a written statement of fact made on oath. The person making it, called the deponent, swears that everything stated is true to their personal knowledge, then signs in the presence of an officer authorised to administer oaths. Once that officer attests it with seal and registration number, the paper stops being a private letter and becomes a legally recognised sworn declaration. The substance is narrow: who you are, the precise window of the gap, what you did during it, and a confirmation of good conduct.
People often confuse this with a gap certificate issued by a college, and the distinction matters in practice. A college-issued gap certificate is an administrative letter from your previous institution; many universities and almost all employers will not accept it on its own and instead insist on a notarised affidavit, because the affidavit attaches criminal liability for falsehood and the letter does not. The affidavit is also broader, since it covers employment breaks that no school would ever certify. If the institution's own portal carries a prescribed form, use that form rather than a generic affidavit, because admissions cells reject mismatched formats far more often than they reject the content. Where no prescribed form exists, the open affidavit drafted on stamp paper is the universally accepted route, recognised across Indian universities, employers and consulates without a central issuing authority behind it.