A promise is a commitment by someone to do or not do something. As a noun promise means a declaration assuring that one will or will not do something. As a verb it means to commit oneself by a promise to do or give. It can also mean a capacity for good, similar to a value that is to be realized in the near future.In the law of contract, an exchange of promises is usually held to be legally enforceable, according to the Latin maxim pacta sunt servanda.