Difference between an Offer & an Invitation to Treat
An invitation to treat is not an offer but an invitation to bid or bargain for an item. For example, at an auction persons may bid on various items presented. An invitation to treat also occurs also when goods are advertised for sale in the media or in shop windows. Goods in a shop window or goods advertised are not an offer by the owners of the goods but are technically an invitation for interested persons to make an offer.