Duplicate bridge is the form of contract bridge where the deals are duplicated (i.e. played by more than 1 table)
There are two types of events: teams or pairs. A team constitutes of four players (one E-W pair and one N-S pair, some events permit stand-by players thus a team with four to seven players is possible). When two teams compete (say A and B), the N-S pair of team A plays with the E-W pair of team B, at the same time, the E-W pair of team A plays with the N-S pair of team B. They exchange their boards after their play so that every board is played by both tables and the result is compared.
In some serious events, the two tables are in separate rooms, namely the closed room and the open room. Spectators are only allowed in the open room and only authorised workers may exchange the boards between the rooms, to minimise the change of passing unauthorised information.
In pair events, the pairs compete and there are no teams. The pairs move in a well defined way such that the comparison is as fair as possible. A board is usually played more than two times unless less than six pairs are competing.
- event or tournament : the entire competition
- session : Large events are divided into sessions. After a session, all movements are completed and all scores are computed.
- round : A round constitutes of a number of boards played by two pairs.
8 boards are normally played in an hour, therefore normally about 20-30 boards are played in a session.
There are two main type of scoring: IMP or MP. See Scoring#Scoring in duplicate bridge for more details. Events are categorised by both the form and the scoring (e.g. IMP pairs).