A unilateral contract consists of a promise for an act, the acceptance by each party to the performance of the act requested, rather than the promise to perform it. It is a Bilateral Contract, as it involves two promises, one made by each party to an agreement. It is not a Unilateral Contract because in a Unilateral Contract, acceptance consists of the performance of the act, rather than the promise to perform it. A voidable contract is one that for some reason a court may set aside at the request of the parties. It differs from a contract that is void, in that a contract that is void cannot be enforced by either party.
Consideration is the price for which a promisor bargains in exchange of the promise.
Whenever a right has been surrendered, or a promise to surrender a right has been made at the request of one on the parties, that promise then becomes un- enforceable. These were established in order to prevent fraud by those who would attempt to establish a valuable contract by false testimony of friends. The Statue of Frauds provided that certain contracts could not be enforced unless the contract was reduced to writing and signed by all parties. This is of course called a Formal Contract.