The previous sections of this module have explained the essential requirements of contract formation. A contract only comes into existence if and when the parties reach sufficient agreement, accompanied by an intention to be legally bound and with either the exchange of consideration or the execution of the agreement in a deed. These requirements must be established with reference to the provable facts of the case. If one or more essential requirement is absent, no contract is created.

That said, there are some special circumstances in which, although the requirements of contract formation are not satisfied, the courts treat the case as if a contract had been made. The relevant doctrine is known as 'promissory estoppel'. 

To understand the nature and scope of promissory estoppel requires drawing some careful distinctions. These are illustrated in the following examples.