Tempo (bridge)
In the card game of bridge, tempo is the timing advantage of being on lead, thus being first to initiate one's play strategy to develop tricks for one's side. Tempo also refers to the speed of play and more generally the rhythm of play over several tricks. According to the rules of the game, the right to select the first card to play ("the opening lead") belongs to the defenders; afterwards, the right to lead belongs to the hand who has won the previous trick. Being on lead generally presents an advantage, as it presents an  opportunity to choose a suit and card which will develop a trick for the leader's side. However, in endplay situations being on lead certainly does not present an advantage—quite the opposite. The tempo can be used for many purposes: Examples. In this extreme example, whoever leads first will take the first 8 tricks, regardless of the denomination. That means that neither side can make any contract, and every contract will fail by at least two tricks—the advantage of having on opening lead makes a three-trick difference. Keeping initiative—"gaining tempo"—by not taking a finesse can be decisive  to prevent the opponents from developing defensive tricks. Against South's 4 west leads the A (indicating the king) and continues with the 8. The opening lead, although natural, was unfortunate, as it gave the declarer a tempo to develop heart tricks for himself. However, it is now essential "not" to take the diamond finesse so as not to lose tempo. South must take the A and play to the A, again refraining from finessing. Now, the declarer can lead hearts for ruffing finesse and discard diamonds until West covers with the K, then ruff and cross over to A , again refusing to finesse. On the remaining hearts, all diamonds including the queen are discarded. In total, the declarer loses one trick in trumps, hearts and clubs each. Note that a diamond opening lead sets the contract, as it doesn't give the tempo in hearts to the declarer: the declarer must lose a heart and two diamonds before he sets up the hearts for diamond discards; the trump king is the fourth trick for the defense. Ethics. It is important that the defenders establish a rhythmic tempo to their play. For example, if declarer is attempting to locate a  particular card, such as an adversely held ace or queen, he may conclude which opponent is most likely to have it based upon a hesitation by that opponent. While the declarer may take advantage of such a hesitation at his own risk, an opponent who deliberately hesitates before making a play with intent to deceive the declarer is guilty of unethical conduct under the of the game and is subject to penalty.