拍卖（英语：Auction），是人类社会特殊的商品交易方式，近现代以来在世界各国广为发展。而拍卖活动是在一定经营理念的指导下进行的。拍卖，各国的法律解释有所不同，中华人民共和国拍卖法给出的定义为：拍卖是指以公开竞价的形式，将特定物品或者财产权利转让给最高应价者的买卖方式。但它不一定准确，还有一些不足，如密封式拍卖缺乏公开性；网上拍卖的公开性也与传统拍卖存在着差距。

而在经济学中，拍卖则有着更深层次的意义，其理论基础来源于信息经济学和博弈论的核心思想，即认为拍卖本身是一个博弈的过程，因而可以通过现代经济学的方法对传统的拍卖方法的效率作出评估，同时也可以设计出新的拍卖方法。

An auction is a process of buying and selling goods or services by offering them up for bid, taking bids, and then selling the item to the highest bidder. The open ascending price auction is arguably the most common form of auction in use today. Participants bid openly against one another, with each subsequent bid required to be higher than the previous bid. An auctioneer may announce prices, bidders may call out their bids themselves (or have a proxy call out a bid on their behalf), or bids may be submitted electronically with the highest current bid publicly displayed. In a Dutch auction, the auctioneer begins with a high asking price for some quantity of like items; the price is lowered until a participant is willing to accept the auctioneer's price for some quantity of the goods in the lot or until the seller's reserve price is met. While auctions are most associated in the public imagination with the sale of antiques, paintings, rare collectibles and expensive wines, auctions are also used for commodities, livestock, radio spectrum and used cars. In economic theory, an auction may refer to any mechanism or set of trading rules for exchange.