when can an offer to form a unilateral contract be revoked
Offer and acceptance An offeror may revoke an offer before it has been accepted, but the revocation must be communicated to the offeree (although not necessarily by the offeror,[16]). If the offer was made to the entire world, such as in Carlill's case,[5] the revocation must take a form that is similar to the offer. However, an offer may not be revoked if it has been encapsulated in an option (see also option contract), or if it is a "firm offer" in which case it is irrevocable for the period specified by the offeror.
Contract A contract is a promise or set of promises that are legally enforceable and, if violated, allow the injured party access to legal remedies. Contract law recognises and governs the rights and duties arising from agreements.[1] In the Anglo-American common law, formation of a contract generally requires an offer, acceptance, consideration, and a mutual intent to be bound. Each party must have capacity to enter the contract. Although most oral contracts are binding, some types of contracts may require formalities, such as being in writing or by deed.