Offer and acceptance
A contract requires agreement: a definite offer by one party that is accepted unconditionally by the other. An offer must be distinguished from an invitation to treat, and acceptance must generally be communicated to the offeror.
Last reviewed 14 June 2026
Shop displays, adverts and goods on a shelf are usually invitations to treat, not offers (Pharmaceutical Society of Great Britain v Boots [1953] 1 QB 401; Fisher v Bell [1961] 1 QB 394) — the customer makes the offer and the seller accepts it.
Acceptance must mirror the offer; a counter-offer destroys the original (Hyde v Wrench). Acceptance must normally be communicated, but under the postal rule it is effective when posted (Adams v Lindsell (1818)).
Key cases
- Pharmaceutical Society of Great Britain v Boots Cash Chemists [1953] 1 QB 401
- Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256
- Hyde v Wrench (1840) 3 Beav 334
Frequently asked questions
What is the difference between an offer and an invitation to treat?
An offer can be accepted to form a contract; an invitation to treat (a shop display, advert or shelf) merely invites others to make offers (Pharmaceutical Society v Boots).
What is the postal rule?
Acceptance sent by post is effective when it is posted, not when received (Adams v Lindsell), unless the offer requires actual communication.