A unique bid auction is a type of strategy game related to traditional auctions where the winner is usually the individual with the lowest unique bid, although less commonly the auction rules may specify that the highest unique bid is the winner. Unique bid auctions are often used as a form of competition and strategy game where bidders pay a fee to make a bid, or may have to pay a subscription fee in order to be able to participate. In practice, such auctions function like lotteries, but the small amount of "skill" involved makes them legal in jurisdictions where lotteries are otherwise illegal. Mechanism This type of auction requires bidders to place bids that are global unique bids. That is, for a bid to be eligible to win no other bidder can have made a bid for the same amount. Bidders are generally able to place multiple bids and the number of current bids at each amount is typically kept secret. There are two major variants of unique bid auctions: In a highest unique bid auction, the bid that is the highest and unmatched when the auction closes is the winning bid. A maximum bid value is usually set at a much lower level than the actual value of the lot. In a lowest unique bid auction, the bid that is the lowest and unmatched when the auction closes is the winning bid. Unique bid auctions will typically allow bids to be very precise, in that each bid can be specific to the 'penny'. For example, a unique bid auction might run as follows: {| class="wikitable" border="1" |- ! Value ! Number of bids ! Comment |- | $0.01 || 34 || |- | $0.02 || 9 || |- | $0.03 || 17 || |- | $0.04 || 57 || |- | $0.05 || 35 || |- | $0.06 || 1 || Lowest unique bid |- | $0.07 || 17 || |- | $0.08 || 0 || |- | $0.09 || 1 || Highest unique bid |- | $0.10 || 100 || |} In a lowest unique bid auction, the bidder who submitted the single bid of $0.06 would win the auction, and would be eligible to purchase the product or service for $0.06, because their bid was the lowest unique bid. In a highest unique bid auction, the bidder who submitted a bid of $0.09 would win the