what is the difference between a contract and promissory estoppel 
in contract law the doctrine of consideration states that there must be an exchange of consideration in order for a contract to be enforced if one party fails to uphold their end of a contract the other party can withdraw from that contract promissory estoppel is the exception to this rule under the doctrine of promissory estoppel even the existence of a promise may be sufficient to enforce an agreement if the other party has suffered damage as a result of acting on that promise 