The "Posting Rule," also known as the "Mailbox Rule," is a legal principle that plays a crucial role in the law of contracts, particularly in the context of offer and acceptance. This rule addresses the moment at which an acceptance of an offer is deemed to be legally effective. According to the Postal Rule, acceptance takes effect when the letter of acceptance is dispatched (that is, placed in the mailbox), not when it is received by the offeror. This principle is significant because it establishes a clear point in time at which a contract is considered to have been formed, even if the acceptance letter is delayed, lost, or never reaches the offeror.