An express contract is an exchange of promises in which the terms by which the parties agree to be bound are declared either orally or in writing, or a combination of both, at the time it is made.
Whether oral or written, the contract must manifest a mutual intent to be bound expressed in a manner capable of being understood, and include a definite offer, unconditional acceptance, and consideration.
Distinguished from a Contract-Implied-in-Fact
A contract implied in fact consists of obligations arising from a mutual agreement and intent to promise where the agreement and promise have not been expressed in words.
An express contract and a contract-implied-in-fact both require mutual assent and a meeting of the minds. However, an express contract is proved by an actual agreement (either written or oral), and a contract-implied-in-fact is proved by circumstances and the conduct of the parties.