Contract bridge awards a bonus for holding a certain combination of high cards), although some are common between the two. A larger bonus is awarded if the declaring side makes a small slam or grand slam, a contract of 12 or 13 tricks respectively. If the declaring side is not vulnerable, a small slam gets 500 points, and a grand slam 1000 points. If the declaring side is vulnerable, a small slam is 750 points and a grand slam is 1,500. In rubber bridge, the rubber finishes when a partnership has won two games, but the partnership receiving the most "overall" points
Contract bridge stay revealed until the first playing card is tabled, after which point the bidding cards are put away. In top national and international events, "bidding screens" are used. These are placed diagonally across the table, preventing partners from seeing each other during the game; often the screen is removed after the auction is complete. Much of the complexity in bridge arises from the difficulty of arriving at a good final contract in the auction (or deciding to let the opponents declare the contract). This is a difficult problem: the two players in a partnership must try to communicate enough information