Which type of contract typically involves promises between two or more parties?

The correct answer is the bilateral contract because this type of contract involves mutual promises made between two or more parties. In a bilateral contract, each party agrees to fulfill certain obligations or promises, which creates a reciprocal relationship. For instance, in a real estate transaction, one party may promise to sell a property, while the other party promises to pay a specified amount in return. This exchange of promises is what fundamentally distinguishes bilateral contracts from others.

In contrast, unilateral contracts involve only one party making a promise, with the other party accepting that promise through their performance, rather than explicit agreement. An implied contract arises from the actions or circumstances of the parties rather than from written or spoken words, indicating that an agreement exists based on behavior. Lastly, an expressed contract is one that is clearly stated, either in writing or verbally, but it does not specify the number of parties involved; thus, it could be either unilateral or bilateral. The characteristics of bilateral contracts are specifically designed for scenarios where mutual commitments are essential to the agreement.