This document discusses key concepts relating to contracts, including offers, acceptance, and communication. It defines a contract as a legally enforceable agreement between two or more persons that requires offer, acceptance, and consideration. An offer is a willingness to enter a relationship, which can be accepted, rejected, or revoked. An invitation to treat is a request for offers rather than an offer. For a valid acceptance, the offeree must accept without modification in the manner required by the offeror and communicate it to the offeror. There are exceptions for ongoing commercial relationships, unilateral contracts, and postal acceptance.