This book present some of the most important bridge bidding systems used in duplicate bridge tournaments, detailing the most known bridge bidding system, Standard American Yellow Card, by using a logical sequential order for openings, answers, competitive bids and defensive play in order to help the players during the games. Much of the complexity in bridge arises from the difficulty of arriving at a good final contract in the auction. A bidding system in contract bridge is the set of agreements and understandings assigned to calls and sequences of calls used by a partnership, and includes a full description of the meaning of each treatment and convention. Standard American Yellow Card is a specific set of partnership agreements and conventions, using Standard American as a base. Standard American Yellow Card is a very specific collection of agreements, which can, of course, be modified and augmented by partnership agreement. In practical use, the term is often mis-used to refer to Standard American in general, or it could refer to a system that used SAYC as a base and made additional augmentations or changes to the base agreements.