What is a written declaration made under oath before an authorized official called?

A written declaration made under oath before an authorized official is referred to as an affidavit. This legal document is often used in various legal proceedings to confirm that the information provided is true to the best of the declarant's knowledge. Affidavits can serve as evidence in court and are foundational in legal contexts where a sworn statement is necessary. They must be signed by the declarant in the presence of a notary public or other authorized official who witnesses the oath.

In comparison, a will is a legal document that outlines how a person's assets will be distributed upon their death, and it does not involve an affidavit's sworn declaration. Testimony refers to the evidence given by a witness under oath during a legal proceeding, but it is typically verbal rather than written. A contract is an agreement between parties that creates legal obligations, but it also does not entail the sworn declaration characteristic of an affidavit.