An affidavit is a written statement made under oath that is typically used in legal proceedings. Learn their purpose, when to use, and how to write.A written declaration upon oath made before an authorized official. Discover a stepbystep guide to creating a general affidavit with Bryan Fagan, PLLC. Understand the legal requirements. Hyphenated words that appear in the reference dictionary as oneword count as one word. Resources and information to help you navigate your court case, including step-by-step guides for following procedures and help with understanding your options. A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court.