Purpose and Example

A bid in opponent's bid or implied suit

Example: 1S - (2H) - 3H

Asking partner to consider 3 Notrump with a stopper, often used at the 3 level.

Example: (2H) - 2S - (P) - 3H
Here, 3H denies stopper

Showing partner a stopper

Example: (2H) - 2S - (P) - 3H
Here, 3H shows stopper

A bid showing first or second round of controls, as Aces & Kings

Example: 1H - 3H; 3S
3S shows the Spade Ace

A bid showing two long suits, usually 5+ cards

Example: (1H) - 2H
2H shows black suits

A bid showing shortness in suit bid

Example: 1S - 4D
4D shows singleton/void

A cuebid by opener over opponent's intervening preemptive bid requesting partner to choice game between either bid suit.  If responder chooses one suit and opener then bids the other suit, opener is showing interest in slam.

Example: 1H - (3D) - 3S - (P);
                 4D
4D requests partner to choose between the majors

A generalized cuebid quering partner for further information

Example: 1C - (1H) - X - (P);
                 2H
2H shows additional values, querying doubling responder for additional information.

A cuebid of opponents' 1 level opening bid, indicating a two-suited hand - specifically the top and bottom (highest and lowest) remaining suits

Example: (1H) - 2H
Shows precisely Spades and Clubs (unlike Michael's Cuebid, playing Tops and Bottoms the lowest unbid suit is always "anchored").

A direct bid of opponent's major suit, showing a long holding in the other colors

Example: 1D - (2D)
Shows length in Clubs and Spades

An advancer bid of opponent's suit, showing strong interest in game.

Example: 1H - (1S) - 2S