What type of contractual agreement is characterized by one party making a promise in exchange for an act by another party?

A unilateral contract is defined by the nature of one party making a promise that is contingent upon the performance of a specific act by another party. In this type of agreement, only one party is obligated to fulfill a promise, while the other party is not required to take any action unless they choose to do so. For instance, in a unilateral contract, a reward is offered for the return of a lost item; the promise of the reward is made, but the obligation to fulfill it only arises if someone finds and returns the item.

This distinguishes it from other types of contracts. A bilateral contract involves mutual promises between two parties, each bound to perform their part of the agreement. An executed contract refers to an agreement in which all parties have completed their respective obligations, and an expressed contract explicitly states the terms of agreement between the parties. Understanding these distinctions is crucial for recognizing the nature of different contractual agreements in real estate and other legal contexts.