What type of contract is defined as one where only one party is required to make an enforceable promise?

A unilateral contract is characterized by the fact that only one party makes an enforceable promise. In this type of contract, the second party does not promise anything in return; instead, they may fulfill the terms set forth by the first party. A common example of a unilateral contract is a reward offer. When someone promises to pay a reward for the return of lost property, they are creating a unilateral contract—only the person making the offer is bound to fulfill the promise of payment upon the completion of the specific action (returning the lost property).

In contrast, mutual contracts involve promises made by both parties, creating obligations on each side. Bilateral contracts require both parties to make mutual promises to each other, which means both parties are bound to fulfill their respective promises. Void contracts are agreements that are not legally enforceable from the moment they are created due to lack of capacity, legality, or mutual assent; therefore, they do not contain enforceable promises from any party.