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,
Bridge convention Bridge convention Contract bridge is a trick-taking card game played by four players in two competing partnerships in which a sequence of , also known as the auction, precedes the play of the cards. The purpose of this bidding is for players to inform their partners of the content of their hand and to arrive at a suitable contract at which to play the hand (or to prevent the opponents from arriving at a suitable contract). Although bidding is often "natural" (describing a hand by simple reference to possession, shape, and strength of the named suit) players may also bid