What is the difference between an offer and an invitation to treat

An offer may be defined as a statement showing a desire to contract on certain terms and to be legally bound by those terms. On the other hand, an invitation to treat is only inviting the party to make an offer. Let’s look at a case that might help explain this:  Pharmaceutical Society of Great Britain v Boots Cash Chemists [1953] 1 QB 401 This case involved medical drugs being sold in a pharmacy. The question was whether the offer was made when the consumer picked up the drugs from the self after having seen the price the shop was offering or whether the contract was concluded when the drugs were purchased at the till. The court held that the drugs were purchased at the till. The advertisement and display of the drugs on the self was a mere invitation to treat. It was an invitation to enter into a contact by purchasing the drugs at the till. To sum up, the key difference is your intention: With an invitation to treat there is no intention that your statement will create a binding contract, whereas with an offer there is.