The transfer of possession of property from one person to another. Under the Sale of Goods Act 1979, a seller delivers goods to a buyer if he delivers them physically, if he makes symbolic delivery by delivering the document of title to them (e.g. a bill of lading) or other means of control over them (e.g. the keys of a warehouse in which they are stored), or if a third party who is holding them acknowledges that he now holds them for the buyer. In constructive delivery, the seller agrees that he holds the goods on behalf of the buyer or the buyer has possession of the goods under a hire-purchase agreement and becomes owner on making the final payment.