A Practice Note discussing common defenses to contract formation available in a common law breach of contract action. It explains how a contract is formed, what makes a contract binding, and offers strategies for disputing a plaintiff's claim that a contract exists. This Note also discusses common affirmative defenses like ambiguity, duress, fraudulent inducement, illegal purpose, lack of capacity, mistake, statute of frauds, unclean hands, unconscionability, and undue influence, and sets out strategies for asserting them in actions where the defendant believes the parties did not form a valid, binding, or enforceable contract.