There are three forms, types, or variations of Bridge
Types of Bridge
Contract Bridge was invented in the 1920's and in the following decades it was popularised especially in the USA by Ely Culbertson. Bridge currently occupies a position of great prestige, and is more comprehensively organised than any other card game. There are clubs, tournaments and championships throughout the world.

Rubber Bridge is the basic form of Contract Bridge, played by four players. Informal social bridge games are often played this way, and rubber bridge is also played in clubs for money.

Duplicate Bridge is the game normally played in clubs, tournaments and matches. The game is basically the same but the luck element is reduced by having the same deals replayed by different sets of players. At least eight players are required for this. There are some significant differences in the scoring. Two types of duplicate bridge will be covered; teams of four and pairs

Chicago Bridge is played by four people (like rubber bridge), but a game is complete in four deals.

Contract Bridge developed from Auction Bridge, which is different mainly in the scoring. In Auction Bridge, overtricks count towards making game, so it is only necessary to bid high enough to win the contract - there is no incentive to bid all the tricks you can make.

Before Auction Bridge there was Bridge-Whist or Straight Bridge (at the time this game was just called Bridge). In Bridge-Whist there is no bidding at all - the dealer either names a trump suit or passes, in which case the dealer's partner must choose trumps. In either case the dealer's partner is dummy. Either opponent may double before the lead to the first trick, and if doubled, the dealer's side may redouble.

Rubber Bridge
Players and Cards
There are four players in two fixed partnerships. Partners sit facing each other. It is traditional to refer to the players according to their position at the table as North, East, South and West, so North and South are partners playing against East and West. The game is played clockwise.

A standard 52 card pack is used. The cards in each suit rank from highest to lowest: A K Q J 10 9 8 7 6 5 4 3 2.

Deal
The cards are shuffled by the player to dealer's left and cut by the player to dealer's right. The dealer deals out all the cards one at a time so that each player has 13. Turn to deal rotates clockwise.

It is traditional to use two packs of cards. During each deal, the dealer's partner shuffles the other pack and places it to the right. The dealer for the next hand then simply needs to pick up the cards from the left and pass them across to the right to be cut. Provided all the players understand and operate it, this procedure saves time and helps to remember whose turn it is to deal, as the spare pack of cards is always to the left of the next dealer.

Bidding
There is next an auction to decide who will be the declarer. A bid specifies a number of tricks and a trump suit (or that there will be no trumps). The side which bids highest will try to win at least that number of tricks bid, with the specified suit as trumps.

When bidding, the number which is said actually represents the number of tricks in excess of six which the partnership undertakes to win. For example a bid of "two hearts" represents a contract to win at least 8 tricks (8 = 6 + 2) with hearts as trumps.

For the purpose of bidding the possible trump suits rank as follows: no trumps (highest), spades, hearts, diamonds, clubs (lowest). A bid of a larger number of tricks always beats a bid of a smaller number, and if the number of tricks bid are equal, the higher suit beats the lower. The lowest bid allowed is "one club" (to win at least 7 tricks with clubs as trumps), and the highest is "seven no trumps" (to win all 13 tricks without trumps).

It is also possible, during the auction, to "double" a bid by the other side or to "redouble" the opponents' double. Doubling and redoubling essentially increase the score for the bid contract if won and the penalties if lost. If someone then bids higher, any previous doubles and redoubles are cancelled.

The dealer begins the auction the turn to speak passes clockwise. At each turn a player may either:

make a bid, which must be higher than the previous bid if any;
say "double", if the previous bid was by an opponent, and has not already been doubled;
say "redouble", if the previous bid was by one's own side and has been doubled by an opponent, but not yet redoubled;
pass, by saying "no bid" or "pass". This indicates that the player does not wish to bid, double or redouble on that round, but a player who has passed is still allowed to bid, double or redouble at a later turn. NB. Either "no bid" or "pass" is permissible, but you should stick to one term or the other. "No bid" is usual in Britain; "pass" is usual in the USA.
If all four players pass on their first turn to speak the hand is said to be passed out. The cards are thrown in and the next dealer deals.
If anyone bids, then the auction continues until there are three passes in succession, and then stops. After three consecutive passes, the last bid becomes the contract. The team who made the final bid will now try to make the contract. The first player of this team who mentioned the denomination (suit or no trumps) of the contract becomes the declarer. The declarer's partner is known as the dummy.

Example of an auction (North dealt):

North East South West
pass 1 heart double 3 hearts
3 spades pass 4 spades pass
pass pass
North-South will try to win at least 10 tricks with spades as trumps; North, who mentioned spades first, is the declarer. South's double of one heart was cancelled by West's bid of 3 hearts.
The Play
The player to the left of the declarer leads to the first trick. Immediately after this opening lead, the dummy's cards are exposed. The dummy should arrange them neatly in suits, so that all the cards are clearly visible, with the trump suit if any to dummy's right (declarer's left).

Play proceeds clockwise. Each player must if possible play a card of the suit led. A player with no card of the suit led may play any card. A trick consists of four cards, and is won by the highest trump in it, or if no trumps were played by the highest card of the suit led. The winner of a trick leads to the next.

Dummy takes no active part in the play of the hand. Whenever it is dummy's turn to play, the declarer must say which of dummy's cards is to be played, and dummy plays the card as instructed (as long as it is legal). Dummy is not permitted to offer any advice or comment on the play. When dummy wins a trick, the declarer specifies which card dummy should lead to the next trick. If when calling for a card the declarer specifies the suit only, dummy is to play the lowest card of that suit.

Scoring
As its name suggests, rubber bridge is played in rubbers. A rubber is the best of three games. A game is won by the first team to score 100 or more points for successful contracts, over several deals if necessary.

A side which has already won one game towards the current rubber is said to be vulnerable. A side which has not yet won a game is not vulnerable. A side which is vulnerable is subject to higher bonuses and penalties than one that is not.

The score is kept on a piece of paper divided into two columns headed WE and THEY, for the two teams, with a horizontal line part-way down (see example). Scores for successful contracts are entered below the line, and count towards winning a game. Other scores, such as bonuses for tricks made in excess of the contract (overtricks), or penalties for tricks short of the contract (undertricks) are entered above the line, and do not count towards winning the game.

Score for making the contract
For a successful contract, the score below the line for each trick (in excess of 6) bid and made is as follows:

If trumps are Clubs or Diamonds, 20 per trick
If trumps are Hearts or Spades, 30 per trick
If there are No Trumps, 40 for the first trick, and 30 for each subsequent trick.
If the contract was doubled the above scores are doubled. If it was doubled and redoubled, they are multiplied by 4.
In addition, the declarer's side scores an extra 50 points above the line if they succeed in a doubled contract. This is sometimes known as "50 for the insult". For making a redoubled contract the bonus is 100 above the line.

Because of the difference in score, clubs and diamonds are called the minor suits and hearts and spades are the major suits.

Slam bonus
A contract to make 12 tricks is known as a small slam. A contract to make all 13 tricks is called a grand slam. For bidding and making a slam, declarer's side get an extra bonus above the line, depending on their vulnerability, as follows:

Slam bonus small slam grand slam
not vulnerable 500 1000
vulnerable 750 1500
Score for overtricks
If the declarer's side wins more tricks than were bid, and were not doubled, then in addition to the score below the line for the contract, they score for the overtricks above the line at the same rate as for bid tricks - i.e. 20 per trick if a minor suit was trumps; 30 per trick in a major suit or no trumps.

If the contract was doubled or redoubled, the bonus for overtricks does not depend on the trump suit, but does depend on whether the declarer's side was vulnerable as follows:

Score per overtrick doubled redoubled
not vulnerable 100 200
vulnerable 200 400
Penalty for undertricks
If the declarer's side win fewer tricks than they bid, neither side scores anything below the line, but the declarer's opponents score above the line. This score depends on the declarer's side's vulnerability, and whether the contract was doubled or redoubled, as follows:

Undertrick penalty: not vulnerable vulnerable

Not doubled - each undertrick: 50 100

Doubled - first undertrick: 100 200
Doubled - 2nd and 3rd undertrick: 200 each 300 each
Doubled - subsequent undertricks: 300 each 300 each
Redoubled undertricks cost twice as much as doubled undertricks.
Honours
The top five trumps (A K Q J 10) are called honours. If one player holds all five of these cards, that player's side scores a bonus of 150 above the line. Four honours in one hand score 100. If there are no trumps, and a player holds four aces, that player's side scores 150 for honours.

Scores for honours are to be claimed at the end of the play (it is assumed that the players will remember what they held).

As there is no skill in scoring for honours, players often agree to play without the honour bonuses.

Game and Rubber
A side that accumulates 100 points or more below the line has won a game. A new line is drawn under the scores. Anything the opponents had below the line does not count towards the next game - they start from zero again.

It is important to notice that, starting from zero and in the absence of doubles, to make a game in one hand you need to succeed in a contract of at least three no trumps, four spades, four hearts, five clubs or five diamonds.

The side which first wins two games wins the rubber. For this they get a bonus of 700 if they won it two games to zero, or 500 if it was two games to one. Both sides scores are then totalled and the side with the higher score wins the difference in money (if playing for money) from the side with less.

If play ends for any reason with a rubber unfinished, then a side with a game gets a bonus of 300 points, and a side with a part score (i.e. a score below the line towards an uncompleted game) gets a bonus of 100.

Example of Rubber Bridge scoring
The scoresheet of a completed rubber might look like this (the letters in brackets refer to the footnotes - they would not appear on the scoresheet):

WE | THEY
|
500 (f) |
50 (f) |
100 (f) |
200 (e) | 500 (i)
300 (b) | 30 (g)
60 (a) | 30 (c)
=============|============== <-- the line
60 (a) | 100 (c)
-------------|--------------
360 (f) | 90 (d)
-------------|--------------
60 (h) | 40 (g)
| 90 (i)

(a) we bid 2 hearts and made 10 tricks - 60 below the line for the contract and 60 above for the overtricks
(b) they bid 4 spades, we doubled them, and they took only 8 tricks - we score 100 for their first undertrick and 200 for the second
(c) they bid 3 no trumps and made 10 tricks. This gives them a game (100 below the line). Another line is ruled to indicate this.
(d) they bid and made 3 spades
(e) they bid two diamonds and made 6 tricks - they are now vulnerable so we score 100 for each undertrick.
(f) we bid 6 hearts; they doubled us, but we won all 13 tricks. We score 360 (180 x 2) below the line for our doubled contract, giving us a game; 100 above for our doubled non-vulnerable overtrick; 50 above for making a doubled contract; and 500 bonus for a small slam bid and made.
(g) they bid one no trump and took 8 tricks; note that their 90 was part of the previous game, so the 40 below does not give them a game.
(h) we bid 3 clubs and made exactly 9 tricks.
(i) they bid 3 hearts and took exactly 9 tricks giving their second game and the rubber, for a bonus of 500 (two games to one).
Adding up the scores, we have 1690 and they have 880. Therefore we have won by 810 points (even though they won the rubber).

* Note on recent changes in scoring
Some details of bridge scoring were changed recently. Before the changes, the penalty for doubled undertricks was 100 for the first and 200 each for all others (and twice as much for a redoubled contract). Also the bonus for making a redoubled contract was 50, not 100, and the bonus for a part score in an uncompleted rubber was 50, not 100.

Partnership agreement and conventions
As in most card games, partners are forbidden to convey information to each other by talking, gestures, facial expression, etc. However there is considerable scope for partners to exchange information within the rules of the game by their choice of bids or cards played.

The bidding mechanism is such that if a player makes a bid (or double or redouble), it is always possible for the player's partner at their next turn to override that bid with a higher bid. This makes it possible for partners to assign arbitrary meanings to bids. Bids which can be taken at face value - that is they convey a genuine wish to play a contract to take the relevant number of tricks or more with the trump suit stated - are called natural. Bids which carry an agreed meaning other than this are called artificial or conventional.

For example if we are partners, we might agree that a bid of one club by me shows a strong hand, but has nothing to do with wanting clubs as trumps. Provided that we both understand this, you will not leave me to play a contract of one club, but will make some other bid, natural or artificial.

The main restriction on agreements between partners about the meaning of bids is that all such agreements must be declared to the opponents. A bidding system is a comprehensive set of partnership agreements about the meanings of bids.

Players should declare their system (if any) at the start of a session. If it is at all complicated, this is done by means of a convention card which sets out the meanings of bids. In addition, any player, at their turn to bid or at the end of the auction, may ask for and be given an explanation of the opponents' bidding agreements. The explanation should be given by the partner of the player who made the bid in question.

Similar considerations apply to the play. Partners may agree on the meaning of the choice of card played in certain circumstances. For example we may agree that when leading from a sequence of adjacent high cards such as K-Q-J we always lead the highest. Again, the opponents are entitled to know about such agreements. They should be declared on the convention card, and may be asked about during the play.

In rubber bridge one does not often come across complicated systems and partnership agreements. One is often playing with an unfamiliar partner, or in an informal setting. Complicated agreements are more often encountered in duplicate bridge, where the players are often long standing partners who have devoted considerable effort to agreeing their system.