In trial practice, the process by which a party attempting to have some sort of evidence admitted at trial must provide sufficient evidence so that a reasonable juror can conclude that the evidence the party seeks to admit is what that party claims it to be. The process of authentication is often referred to as "laying a foundation" for the evidence desired to be admitted at trial. There are several different methods that can be used to authenticate evidence, including testimony by a witness with personal knowledge on the authenticity of the evidence.

With regards to contracts or other documents, to sign or to execute the document.