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,
Jump bidding Jump bidding In auction theory, jump bidding is the practice of increasing the current price in an English auction, substantially more than the minimal allowed amount. At first glance, jump bidding seems irrational. Apparently, in an English auction, it is a dominant strategy for each buyer whose price is above the displayed price, to always bid the minimal allowed increment (e.g. one cent) above the displayed price. By bidding higher, the bidder gives up the opportunity to win the item at a lower price. However, in practice buyers increase the displayed price much more than the minimal allowed increment. Often,