What type of contract can involve both parties making promises to each other?

A bilateral contract is defined by the mutual exchange of promises between two parties, where each party commits to fulfilling certain obligations. In essence, both parties are obligating themselves to perform actions or provide goods or services, thereby creating a legal binding agreement. For example, if one party agrees to sell a car and the other agrees to pay a specified amount for it, this mutual promise forms a bilateral contract.

In contrast, a unilateral contract involves only one party making a promise, where the other party accepts that promise through action rather than a reciprocal promise. Implied contracts are those that are inferred from actions or circumstances rather than explicitly stated, and expressed contracts are those that are clearly stated, either verbally or in writing. However, they do not necessarily require both parties to promise anything to each other, which is the defining characteristic of a bilateral contract.