The Jacoby transfer, or simply transfers, in the card game contract bridge, is a convention in most bridge bidding systems initiated by responder following partner's notrump opening bid that forces opener to rebid in the just above that bid by responder. For example, a response in diamonds forces a rebid in hearts and a response in hearts forces a rebid in spades. Transfers are used to show<!-- a weak hand with--> a long suit, usually a major, and to ensure that opener the hand if the final contract is in the suit transferred to, preventing the opponents from seeing the cards of the stronger hand.
The use of the 2 and 2 (and often 2) responses to an opening 1NT bid as transfers is one of the most widely employed conventions in the game. Less commonly, partnerships may agree to use transfer-style bids in a variety of other situations.
History and purpose
First described in a series of articles by Olle Willner of Sweden in Bridge Tidningen in the early 1950s, transfers were popularized for English speakers in 1956 in The Bridge World article by Oswald Jacoby and have gained widespread international acceptance by duplicate and rubber bridge players alike. In the article, Jacoby gave his name to the convention as the Jacoby Transfer Bid (JTB) stating that it was an adaptation of a bid then known variously as either the 'Texas Convention' or the 'Carter Transfer' (now known as the Texas transfer), which was used at the 4 level rather than the 2 level.
The initial purpose of the convention was to make the notrump opener the declarer in a suit contract when his partner held a relatively weak hand with a long suit. This would make the opening lead present first to the weaker hand (which next will be exposed as the "dummy" hand), a situation advantageous should declarer possess one or more or tenuously guarded honors. In addition, the exchange of information by the transfer bid and subsequent rebids by responder and notrump opener "is designed to help partnerships reach the right contract"