Offer and acceptance are two essential elements required to form an enforceable contract. An offer is made when one party makes a promise to do or refrain from doing some specified act in the future. And an acceptance occurs when an offer is accepted unequivocally—without conditions or ambiguity.
In other words, the acceptance must mirror the terms of the offer. If the acceptance varies from the terms of the offer it is considered a rejection of the offer and a counteroffer.
Acceptance may be expressed through words, deeds, or the performance called for in the contract.
In California, the formation of a contract requires an offer, acceptance, and consideration. An offer is a clear promise to be bound under certain terms, and it must be communicated to the offeree. Acceptance must be unequivocal and must mirror the terms of the offer exactly, which is known as the 'mirror image rule.' If the acceptance alters the terms or adds new ones, it is not a true acceptance but rather a counteroffer, which the original offeror can then accept or reject. Acceptance can be communicated through words, written or oral, or through actions that clearly indicate acceptance of the terms, such as beginning the performance of the contract. Under California law, the acceptance must be communicated to the offeror unless the offeror has waived the need for communication. This is in line with the general principles of contract law in the United States.