Authentication is the process of proving that a document, photograph, electronic communication, or other piece of evidence is genuine that it is what the offering party claims it to be. Authentication is required before evidence can be admitted.

Common authentication methods include testimony from a witness with personal knowledge, evidence of distinctive characteristics combined with other evidence, testimony about where a document was found, or expert testimony.

Text messages and social media posts require authentication that someone must establish that the message came from the claimed sender. Metadata, contact names, phone numbers, and corroborating context all contribute to authenticating electronic communications.