Contract bridge grand slam exists. The modern game of contract bridge was the result of innovations to the scoring of auction bridge by Harold Stirling Vanderbilt and others. The most significant change was that only the tricks contracted for were scored below the line toward game or a slam bonus, a change that resulted in bidding becoming much more challenging and interesting. Also new was the concept of "vulnerability", making sacrifices to protect the lead in a rubber more expensive. The various scores were adjusted to produce a more balanced and interesting game. Vanderbilt set out his rules in 1925, and within
Bidding box in 1962 in Sweden by Gösta Nordenson and first used at a World Bridge Championships game in Stockholm in 1970. Eric Jannersten, a Swedish social bridge player and founder of the largest European bridge equipment manufacturer, Jannersten Förlag AB bought the patent in 1970 being attributed by some as the inventor. However, the patent is disputed by the Swedish Bridge Federation. They quickly became popular in Europe, and after some resistance were accepted in American bridge clubs. , they are practically an indispensable part of the game, and even many rubber bridge players use them at home. Use of bidding