There are several circumstances under which an agreement or an offer may be terminated. The first way to terminate an offer is to attempt to change the offer. Any attempt to change an offer is known as a counter-offer. A counter-offer is a termination of an offer by the offeree. If a counter-offer is presented and subsequently rejected, the execution of the original offer cannot be compelled by a court of law. Unless the counter-offer contains a provision specifically authorizing it, any previous offer becomes invalidated.
An offeror may terminate an offer if the offer contains a time period during which the offer must be accepted. If the offer does not contain a time period after which the offer becomes invalidated, then the courts commonly hold that the offer is invalid after a "reasonable" amount of time, but never specifically states what that time period is. In the event an offeror rescinds the period of time for which they had previously agreed to keep an offer open, the offeree can sue for breach of contract.
Contract negotiations are often lengthy processes. If during the negotiations one of the parties discovers that the information being discussed in the negotiations is substantively different than as presented during the negotiation process but fails to disclose this information, it may serve as grounds to invalidate the other party's agreement.