UCC Article 4 is part of the Uniform Commercial Code, which governs commercial transactions in the United States. Specifically, Article 4 deals with bank deposits and collections, outlining the rights and responsibilities of banks and their customers regarding checks and other payment instruments. This article establishes rules for the processing of checks, including how they are presented, accepted, and paid. It also addresses issues like the liability of banks for unauthorized transactions and the responsibilities of customers to report errors or fraud in their accounts.