Bidding box for home-played games. Use of bidding boxes has several advantages over oral bidding: it reduces noise in the room, prevents bidding being overheard at neighboring tables, allows easier review of the auction, and reduces the opportunity to pass unauthorized information to one's partner (intentionally or not) by the manner and intonation in which one makes one's bid. A bidding box is typically a plastic box with two slots, each containing a set of bidding cards. One slot contains 35 cards with symbols of bids (5 denominations—clubs (), diamonds (), hearts (), spades (), and notrump (NT)—in seven levels of bidding,
Auction sniping placed multiple incremental bids as the auction progresses. Many online auctions use proxy bidding, an iterative sealed bid auction where winners pay a fixed increment over the second highest bid. The auctioneer does not disclose the current maximum bid, but the second highest bid is always public. In proxy bidding, the wise bidder must know in advance the "true" value of an item as a basis for their secret bidding limit. The fact that the maximum bid is revealed when it is outbid introduces the possibility of maximum bid fishing. Bidders unsure of the value of an item may incrementally