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
History of contract bridge auction bridge made by Harold Stirling Vanderbilt and others. The most significant change was that only the tricks contracted for were counted below the line towards game and slam. That made bidding much more challenging and interesting. Another innovation was the concept of "vulnerability", a difference in the sizes of penalties incurred by partnerships that have or have not won one game. That discouraged sacrifice bidding to protect the lead in a rubber. Some other scores were adjusted to produce a more balanced game. Vanderbilt set out his rules in 1925, and within a few years contract bridge had so