The sale of a given object through bids, in which the object goes to the highest bidder, is known as an auction. In economic terms, an auction refers to a system of resource allocation characterised by a variable, unset price, for which a minimum is established (the reserve price): if the bids do not exceed this price, the sale does not take place.

Online auctions, which, like many other sectors, make it possible to benefit from the function advantages of a tool such as the Internet, are experiencing significant development (thanks partly to the growing popularity of specialised websites). Although the web is primarily used to buy and sell items of a limited value, a transformation is currently taking place from systems limited in space and time towards a global market with particularly dynamic prices, to the point that top international auction houses are now starting to hold auctions on the Internet.