An auction is a method of asset sale by competitive bidding. An auction is most useful when the potential price of the asset to be sold is uncertain. Different auction formats exist, varying according to how prices are quoted and bids tendered.
The most commonly known of these is the English Auction, which is commonly used for artworks and wine. This auction is also called the ascending price or open-outcry auction. The best known auction houses, Sotheby's and Christie's, were founded in the eighteenth century, but written records of auctions go back to ancient times.
Economists specializing in game theory have investigated the theory of bidding strategies for an auction, and how these strategies depend upon the rules and procedures of the auction. In the business arena, these experts are sometimes hired as consultants for important auctions, such as when the Unites States government sold wireless spectrum licenses by auction.

An online travel auction is a system of buying and selling travel products and services online by proffering them up for bid and then awarding the item to the highest bidder.
As with a standard (offline) auction, the bidders, having made a judgment on how much a particular product is worth to them, place their bid over a set period of time. At the end of this period of time, the highest bidder ‘wins’ the product at whatever price is finally reached.