Contracts are promises that the law will enforce. The law provides remedies if a promise is breached or recognizes the performance of a promise as a duty. Contracts arise when a duty does or may come into existence, because of a promise made by one of the parties. To be legally binding as a contract, a promise must be exchanged for adequate consideration.
Adequate consideration is a benefit or detriment which a party receives which reasonably and fairly induces them to make the promise/contract . For example, promises that are purely gifts are not considered enforceable because the personal satisfaction the grantor of the promise may receive from the act of giving is normally not considered adequate consideration. Certain promises that are not considered contracts may, in limited circumstances, be enforced if one party has relied to his detriment on the assurances of the other party.
Contracts are mainly governed by state statutory and common (judge-made) law and private law. Private law principally includes the terms of the agreement between the parties who are exchanging promises. This private law may override many of the rules otherwise established by state law.
Statutory law may require some contracts be put in writing and executed with particular formalities. Otherwise, the parties may enter into a binding agreement without signing a formal written document. See § 110 of The Restatement. Most of the principles of the common law of contracts are outlined in the Restatement Second of The Law of Contracts published by the American Law Institute. See Restatement (Second) of Contracts. The Uniform Commercial Code, whose original Articles have been adopted in nearly every state, represents a body of statutory law that governs important categories of contracts. The main Articles that deal with the law of contracts are Article 1 (General Provisions) and Article 2 (Sales).
Sections of Article 9 (Secured Transactions) governs contracts assigning the rights to payment in security interest agreements. Contracts related to particular activities or business sectors may be highly regulated by state and/or federal law.See Law Relating To Other Topics Dealing with Particular Activities or Business Sectors.
In 1988, the United States joined the United Nations Convention on Contracts for the International Sale of Goods which now governs contracts within its scope.