Consideration and promissory estoppel are crucial elements in contract law. Consideration represents the bargained-for exchange of value between parties, while promissory estoppel serves as an equitable remedy when a contract lacks consideration but enforcing the promise is necessary to avoid injustice. These concepts have evolved from English common law to modern contract theory. Understanding their elements, exceptions, and practical applications is essential for grasping how courts determine the enforceability of promises and agreements in various contexts.