The two primary categories of contract bridge scoring are known as duplicate scoring and rubber scoring. In both variations, scores are kept by making tick marks on a score sheet divided into identical sections for each player. The American Contract Bridge League provides detailed scoring instructions for both rubber and duplicate versions of bridge, as well as subvariations such as Chicago bridge.
The objective of rubber bridge is to score the most total points in a set of three games, called a rubber. Rubbers end once one side has twice accumulated at least 100 contract points "below the line," or below the main horizontal line of the score sheet. Trick points are recorded below the line when a contestant makes a contract. Extra points are recorded above the line for holding honor cards in trumps, winning a rubber, fulfilling redoubled contracts and a number of other secondary goals. Chicago bridge, also known as club bridge, is a form of rubber bridge in which each round consists of four deals and vulnerability is not determined by previous scores.
Duplicate bridge scoring is similar to rubber bridge, but every deal is scored independently from every other deal. No part scores are carried forward in duplicate bridge, and trick point values are doubled for both doubled contracts and redoubled contracts.