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 New York, as in other jurisdictions, the formation of a contract requires an offer, acceptance, consideration, and mutual assent. An offer is a clear proposal made by one party (the offeror) to another (the offeree), indicating a willingness to enter into a contract on certain specified terms. Acceptance, on the other hand, must be an unequivocal assent to the terms of the offer without modification; it must mirror the offer exactly. This 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 in various ways, including verbally, in writing, or through conduct that clearly indicates acceptance of the offer's terms, such as performing the actions specified in the contract. New York follows the common law of contracts, and these principles are applied in both state and federal courts when adjudicating contract disputes.