Rubber bridge is the original form of contract bridge, played by two partnerships.
Rubber bridge is played in rubbers. A rubber is won by a partnership who wins two games. After a rubber has been finished, or has been prematurely terminated, the scores are added to determine the final result. See scoring#Scoring of rubber bridge for details.
The deal Edit
Two decks are used alternately. If the partnerships are formed by drawing, a card is then drawn by each player to determine the partnership. The players with two higher cards form the partnership, in which the higher one is the initial dealer.
The dealer's LHO shuffles one of the decks, and his partner shuffles the other. In each subsequent deals, the partner of the dealer shuffles the deck not in use. Therefore, the dealer rotates in turn and it is always the dealer's LHO who shuffles the deck. Before dealing, the dealer may shuffle it. 
Before dealing, the deck must be cut by the dealer's RHO, by taking a portion not less than 4 cards and places it on the table. The dealer than places the remaining portion, also not less than 4 cards, on the top of another portion to complete the cut. 
The auction Edit
The auction follows the general principle of contract bridge, in short, a player can make a sufficient bid, double if the last action is an opponent's bid, or redouble if the last action is an opponent's double. If the deal is passed out, the deal is abandoned and the next dealer deals.
The play Edit
The play follows the general principle of trick-taking card games, in short, players have to follow suit, and the winner of a trick leads to the next. In rubber bridge, a trick is gathered and put in front of a member of the winning side (either the declarer or one of the defenders).
Differences to duplicate bridge Edit
- The tricks are gathered together in rubber bridge, while the cards absolutely cannot be mixed together in duplicate bridge.
- The opening lead is done face down in duplicate bridge, but not a common practice in rubber bridge.
- A passed out deal is abandoned in rubber bridge and not scored, but is scored as 0 in duplicate bridge.
- Partscores accumulate to games in rubber bridge, but not in duplicate bridge.
- The decks are shuffled and dealt for each deal in rubber bridge, but are only shuffled and dealt once in duplicate bridge, before the start of the session.
- absolute safety play: it is not worth risking the contract for a line of play which will produce overtricks when successful.
- less doubles: a double may turns a partscore into game
- no sacrifices: a sacrifice only preserve the state of the rubber, and an unsuccessful sacrifice may cost even more than the value of a rubber (700 points).
Also, the choice of denomination is not important: you just bid whatever which is the safest to make.
Moreover, the carry-over nature of rubber bridge also produces some tactics not exist in duplicate bridge:
- As there is a bonus of 150 points with four aces in NT, players prefer plays in NT even with some unbalanced hands with all aces.
- Any bid beyond game level indicates a slam interest. For example, with we have 70 points in the partscore, 1♠-2♠ indicates a slam interest in spades.
- Player may stretch to complete a game if they have a partscore on. For example, a 15-17 1NT will become something like 10-20 if we have 60 points on.