The distinction between an offer and an invitation to deal is clear and its consequences are well-known. Whilst the former bestows upon the offeree the power to accept and thus to conclude the contract, the latter is only intended to elicit an offer which the tenderer is then at liberty to accept or reject. It is, by contrast, less simple to determine when we are faced with an offer or an invitation to deal, or which of these might alone apply according to the rules of one or other legal system.
In this paper we do not intend to touch upon the questions involved in an overture to a specified individual or an announcement of a reward to the public for the performance of some act, i.e., to the person who carries out the required act (although, as happens in English law, such a case also falls under contract and is not regarded as a unilateral promise effective in itself). Instead we shall deal with overtures to the public indicating that a person has goods or services to supply, which take the form of displaying wares in a shop window or in the interior of a shop (sometimes by inviting customers to utilize self-service facilities) or of distributing catalogues, price lists, handbills, advertisements, posters and the like.