This chapter aims to introduce engineers to the Uniform Commercial Code (UCC). The motivation of the UCC is to reduce the variety of provisions in interstate contracts to facilitate interstate commerce within the United States and its possessions. UCC contracts grew out of and are based on common law contracts. In UCC contracts for sales, the parties are, for certain aspects, divided into merchants and the public. The offer and acceptance model of the common law applies to UCC sales contract formation except that a suitable acceptance may be valid even if it includes terms different from those proposed in the offer. The chapter discusses a case relates to the so-called shrink-wrap licenses on software that constitute a contract that prohibits buyers from copying the software for resale. The case illustrates how the UCC provides flexibility in the formation of contracts that did not exist in common law contracting.