Quantum meruit allows a party to a contract to recover the value of work performed if the contract is not completed due to breach by the other party. It is based on an implied promise to pay for benefits received. Claims can arise in cases of void agreements, non-gratuitous acts, acts preventing completion, divisible contracts where benefits were received, and indivisible contracts completed but performed badly. Recovery is limited to the value conferred rather than full payment due under the original terms.