A paper trail refers to a documented record or evidence that is created and maintained in written form. It typically involves keeping copies of important documents, such as contracts, receipts, letters, emails, etc., which can serve as proof of events, transactions, communications, or decisions made. The phrase "paper trail" suggests a systematic approach to maintaining records that are tangible and easily accessible for reference purposes. It is often used in the context of official investigations, audits, or legal proceedings where evidence is required to establish facts or determine accountability.