Bid a contract with your partner, then go out and make it.
The most demanding partnership card game there is. Four players in two partnerships, thirteen tricks per deal, and an auction beforehand that decides what you are trying to do.
A 52-card deck, all of it dealt out, thirteen cards each. Aces are high. Partners sit opposite each other and are referred to as North-South and East-West.
Before any card is played, the partnerships bid for the contract. A bid names a number of tricks above six and a trump suit — so "two hearts" is a promise to take eight tricks with hearts as trump. Suits rank clubs, diamonds, hearts, spades, and no-trump above them all. Each bid must be higher than the last, and the auction ends after three consecutive passes.
You may also double an opponent's contract to raise the stakes, and they may redouble.
The partnership that made the final bid is the declaring side. The one who first named that denomination is declarer; their partner is dummy and lays their entire hand face up on the table once the opening lead has been made. Declarer then plays both hands.
The player to declarer's left leads. You must follow suit if you can, otherwise you may play anything. The highest trump wins, or failing that the highest card of the suit led. The winner leads next.
Make the contract and you score for the tricks bid, with more per trick for the higher suits and no-trump. Overtricks score extra. Fail, and the opponents score for every trick you fell short.
A partnership that accumulates 100 contract points wins a game, and two games win the rubber. Bidding a contract worth 100 in one deal — game — is the ordinary goal, which is why three no-trump, four hearts and four spades are the bids you will hear most.
Bids do more than name a target: they describe your hand to your partner within an agreed system. That is the whole art of the game, and it is why two people who have played together for years beat two better card players who have not.