How can an offer be kept open?

An offer can be kept open by explicitly stating a time frame during which the offer remains valid, often referred to as a "firm offer." Additionally, the offeror can communicate their intention in writing to keep the offer open for a specified period, ensuring that the offeree is aware of the timeline. In some cases, consideration may be required to support the promise to keep the offer open, such as a small payment. Finally, the offer can be kept open until it is either accepted, rejected, or revoked by the offeror.