What type of contract is characterized by only one party making a promise?

A unilateral contract is defined by a situation in which only one party makes a promise, often in exchange for an act performed by the other party. This type of contract becomes binding when the other party fulfills the condition of the promise. For example, if someone offers a reward for the return of a lost item, the promise is made unilaterally. The person who returns the item is not obligated to do so, but if they choose to, they fulfill the terms of the contract and can claim the reward.

In contrast, mutual contracts require promises from both parties, establishing obligations on each side. Bilateral contracts involve both parties exchanging promises, meaning each party is both a promisor and a promisee. Voidable contracts are valid contracts that can be legally voided at the option of one party due to certain circumstances, such as misrepresentation or undue influence.

Thus, the defining feature of a unilateral contract is its characteristic of providing a promise from only one party, which distinguishes it from the other types of contracts listed.