According to the document, contract law deals with enforceable agreements between parties. There are several key elements for a valid contract, including offer and acceptance, lawful consideration, capacity and consent of parties. Contracts can be classified in various ways, such as by method of formation (express, implied, quasi), time of performance (executed, executory), parties involved (bilateral, unilateral), and validity (valid, void, voidable). Commercial law regulates transactions and covers areas like contracts, negotiable instruments, sale of goods, partnerships, and companies.