Rule 1401 (a) Authentication of a writing is required before it may be received in evidence.

Before a document can be used as evidence in court, someone must first prove that the document is real and what it claims to be. This is called authentication.

This applies both to the original document and to any copies or descriptions of what the document says. You cannot just hand a judge a letter or contract and expect it to be accepted. You need to show the court that the document is genuine.