Which type of contract primarily focuses on one party's obligation without a reciprocal obligation?

In the context of contracts, a unilateral contract is one where only one party is bound to perform their obligation. This means that while one party has a duty to fulfill a specific action, the other party has no corresponding obligations. A classic example of this is a reward contract, where one person promises to pay for the return of lost property. The offeror is obliged to pay the reward upon completion of the task, but the person who finds the property has no obligation to search for it.

This highlights the nature of unilateral contracts, emphasizing the lack of a reciprocal obligation. The focus is solely on the obligation of one party, which is the defining characteristic that separates it from other types of contracts. In contrast, other types—such as gratuitous contracts, which involve one party providing a benefit without expecting anything in return, or onerous contracts, which involve mutual obligations—do not fit this definition as they incorporate reciprocal responsibilities. Aleatory contracts, depending on an uncertain event, also generally imply mutual obligations between the parties involved. Thus, understanding the concept of unilateral contracts is crucial in distinguishing types and the responsibilities they entail.