 Contracting parties are regularly referred to as “promisor” and “promisee”. Where there are multiple parties to a contract, the Restatement provides that “some or all of them may promise jointly as a unit, or some or all of them may each promise severally”. Although the Restatement does not state what a promise is, it defines offer and acceptance, the pair of acts through which contractual obligations characteristically arise, in terms that involve an exchange of promises. An “offer” is