This introductory chapter provides an overview of contract law and its application. A contract is an agreement made with intention that it will be legally enforceable. Contract law concerns issues regarding the formation of contracts; the sources, interpretation, and regulation of terms; when a breach takes place and the resulting consequences; and ways to escape a contract through vitiating factors, mistake, or frustration. The parties’ intentions are determined using an objective approach based on the standard of the reasonable person. A lot of contract law can be understood as default rules to apply when the parties have not been clear enough about their intentions. The law of contract also concerns foundational principles and mainly consists of common law rules. Many cases still give effect to the values of the classical model, which is based on the freedom and sanctity of contract, and a view that contracting parties are self-interested. The most significant recent development away from the classical model is the recognition of relational contracts and an implied obligation to act in good faith.