Offer and acceptance.

Contract law: offer and acceptance An offer is a definite promise to be bound on certain terms. It can be made to one person or to the whole world (Carlill v Carbolic Smoke Ball Co, 1893 — advert promising £100 was a unilateral offer, accepted by performing the conditions). An invitation to treat is NOT an offer: goods displayed in a shop window (Fisher v Bell, 1961), goods on shop shelves (Pharmaceutical Society v Boots, 1953), most adverts (Partridge v Crittenden, 1968). A counter-offer destroys the original offer (Hyde v Wrench, 1840). A mere request for information does not (Stevenson v McLean, 1880). Acceptance must be communicated to the offeror. Silence cannot amount to acceptance (Felthouse v Bindley, 1862). Instantaneous communications take effect when received (Entores v Miles Far East, 1955). The postal rule: acceptance by post takes effect when the letter is posted, not when it arrives (Adams v Lindsell, 1818), provided post was a reasonable method of acceptance. Revocation of an offer must be communicated before acceptance, and can come through a reliable third party (Dickinson v Dodds, 1876).