Final answer:
A valid contract requires offer and acceptance, consideration, and competent parties. Written evidence is not always required for a contract to be enforceable, except for certain contracts under the Statute of Frauds.
Step-by-step explanation:
The elements of a valid contract typically include an offer, acceptance of that offer, consideration (a promise or payment to support a contract), and competent parties who have the legal capacity to contract. Each element must be present for a contract to be legally enforceable.
The element that is not necessarily required for a contract to be valid is written evidence. While some contracts must be in writing to be enforceable under the Statute of Frauds (such as contracts involving the sale of real estate), many other contracts can be verbal and still be legally binding.