Cappalletti: A defense to 1NT openings in which 2C shows a single-suited hand, 2D shows both majors, 2H shows hearts and a minor, and 2S shows spades and a minor. In response to 2C, 2D asks for overcaller's suit. In response to 2H or 2S, 2NT asks for overcaller's suit.
Checkback Stayman: 2C in response to opener's 1NT rebid is forcing and artificial and requests additional information about opener's hand.
Constructive raises: A single raise of a major-suit opening shows 8-10 points.
DONT: A defense to 1NT openings in which Double shows a single-suited hand, 2C shows clubs and another suit, 2D shows diamonds and a major suit, and 2H shows both majors. In response to Double, 2C asks for overcaller's suit.
DOPI: After interference over Blackwood, double (or redouble) shows 0 aces, pass shows 1 ace, the cheapest bid shows 2 aces, and the next-cheapest bid shows 3 aces.
Drury: 2C by a passed hand in response to a suit opening bid asks opener if he has full opening-bid values. Opener is expected to rebid his suit with full values or bid 2D with a subminimum.
Flannery: Opening 2D shows 5 hearts, 4 spades, and 11-15 HCP. In response, 2NT is forcing and asks for further information.
Fourth suit forcing: Responder's rebid of the fourth suit is artificial and forcing.
Gerber: Over partner's natural 1NT or 2NT bid, 4C asks for aces. In response, 4D shows 0 or 4 aces, 4H shows 1, 4S shows 2, and 4NT shows 3 aces. The Gerber bidder may then ask for kings by bidding 5C, with similar responses.
Grand slam force: When a suit has been agreed, 5NT asks partner to bid a grand slam if his trumps include two of the top three honors in the suit.
Inverted minor suit raises: A single raise of a minor-suit opening is forcing, showing invitational or better values, while a double raise is preemptive with 6-9 points and 5-card support.
Jacoby 2NT: 2NT in response to a major-suit opening is a game-forcing raise. In response, opener shows a singleton if he has one. Without a singleton, opener bids four of his suit with a balanced minimum, 3NT with extra values, or three of his suit with a maximum.
Jacoby transfer: In response to a 1NT or 2NT opening, a minimum bid in D or H shows five or more H or S respectively, and asks opener to bid the next step.
Journalist leads: A style of honor opening leads against notrump contracts. Lead of the ace shows a semisolid suit and asks partner to unblock an honor or give a count signal. The king is led from AK or KQ. The queen is led from QJ or KQT9; partner should unblock the jack if possible. The jack shows JT and denies a higher honor; the nine shows T9 or 98 and denies a higher honor. The ten is led from any interior sequence in a holding including the ace, king, or queen; AJT, KT9, AQT9, etc.
Lebensohl: When the opponents overcall partner's 1NT opening, 3-level bids show strength, and 2NT by responder shows a weak hand and asks opener to bid 3C, after which responder can sign off. This can also be played after partner's double of a weak two bid.
Michaels: After an opponent's opening of one of a suit, two of that suit shows a two-suiter, either weak or very strong, including all unbid majors. If the Michaels bid is two of a major, then a response of 2NT asks opener to show his minor suit.
Minor suit Stayman: In response to a 1NT or 2NT opening, a minimum bid in spades shows a good hand and asks opener to bid a 4-card minor.
Namyats: An opening bid of 4C or 4D shows a strong preempt in hearts or spades, respectively.
New minor forcing: Two of an unbid minor in response to opener's 1NT rebid is forcing and artificial and requests additional information about opener's hand.
Responsive doubles: After partner's overcall or takeout double, double of a raise is takeout.
Reverse Drury: 2C by a passed hand in response to a suit opening bid asks opener if he has full opening-bid values. Opener is expected to bid rebid his suit with a subminimum or bid 2D otherwise.
RKCB (Roman Key Card Blackwood): A form of Blackwood where the king of the agreed trump suit is treated as a "fifth ace". In response, 5C shows 0 or 3 "aces", 5D shows 1 or 4, 5H shows 2 without the queen of trump, and 5S shows 2 with the queen of trump. A new-suit rebid by the RKCB bidder below five of the agreed suit asks for the queen of trump.
Rusinow leads: On opening lead, leading second-highest from a sequence. (Examples: K from AK, Q from KQ, T from JT, T from KJT, J from QJT, etc.)
Soloway jump shifts: A jump in a new suit in response to partner's one-level suit opening bid shows 16+ points in one of several specific hands, clarified by the rebid. A rebid in NT shows 18+ points, balanced or semibalanced. Rebid of responder's suit shows a six-card or longer suit headed by AKQ. Rebid of a new suit shows a singleton or void and at least four cards in support of opener's suit; rebid of opener's suit shows a 5422 distribution.
Splinter: A jump (usually a double jump) in a new suit showing a singleton or void in the named suit and support for partner's last-bid suit. This is forcing to game and suggests slam possibilities if partner has well-placed values.
Support doubles: After a one-level major-suit response to an opening bid, and a low-level overcall or double by the next hand, a double or redouble by opener shows exactly three-card support for responder's major. A raise thus promises four-card support.
T/9 coded: The opening lead of a 10 or 9 against a notrump contract is from an interior sequence and shows either 0 or 2 higher cards.
Texas transfers: In response to a 1NT or 2NT opening, 4D or 4H shows a hand wishing to sign off in 4H or 4S respectively, and asks opener to bid the next step.
The Law: A general principle of competitive bidding. Add the lengths of North-South's longest trump suit and East-West's longest trump suit. Add the number of tricks that North-South can make in their best trump suit, and the number of tricks that East-West can make in their best trump suit. These two sums will often be identical.
Truscott: After a takeout double of an opening bid, 2NT by responder shows a limit raise of opener's suit, and three of opener's suit is preemptive.
Unusual notrump: A jump overcall of 2NT, or (less often) an overcall of 4NT, showing length in the two lower unbid suits.
Western cue bid: A bid of an opposing suit that shows a partial stopper, hoping that partner can then bid notrump.
3rd/5th: On opening lead, the lead of a low card is either third-best from an even-length suit, or the lowest of an odd-length suit.
4th best: On opening lead, the lead of a low card is the lowest of a three-card suit or the fourth-best card of a longer suit.