<human>:  What are the four elements of a valid contract?
<bot>: 
1. Offer: One party must offer something of value to the other party.
2. Acceptance: The other party must accept the offer from the first party.
3. Consideration: Both parties must provide something of value, usually money, as consideration for the promise.
4. Capacity: Both parties must have the legal capacity to enter into a contract, and must do so willingly.