Stayman
The convention Stayman is played when your partner opens 1NT, promising a hand with 15-17 pts. and is balanced. It can equally be played with a stronger 2NT opening hand which promises 20-21 pts. and is balanced.
It is used by a partnership to find a 4-4 or 5-3 trump fit in a major suit. If you have a 4 and a 5 card major and a minimum of 8 points, you should always play Stayman first. It is also possible to play Stayman after a 1NT Overcall.
After an opening bid or an overcall of 1NT [2NT] responder or advancer bids an artificial 2 Clubs [or 3 Clubs after 2NT] to ask opener or overcaller if he holds a four-card major suit and with a minimum of 8+ points.
The artificial club bid typically promises four cards in at least one of the major suits with enough strength to continue bidding after partner's response. A strength of 8 HCP for an invitational bid opposite a standard strong 1NT opening or an overcall showing 15-17 HCP, or 5 HCP to go to game opposite a standard 2NT showing 20-21 points.
It also promises distribution that is NOT 4-3-3-3. By invoking the Stayman convention, the responder takes control of the bidding since the strength and distribution of the opener's hand is already known 15-17 or 20-21 pts.
The opener responds with either of the following 3 rebids:
- 2 Diamonds [3 Diamonds] denies having 4 or more cards in either major suit
- 2 Hearts [3 Hearts] shows at least 4 hearts but does not deny 4 spades
- 2 Spades [3 Spades] shows at least 4 spades and denies having 4 hearts
A notrump opener should have neither a suit longer than five cards nor more than one 5-card suit since an opening notrump bid shows a balanced hand. A notrump bidder who has at least four cards in each major suit normally responds in hearts first.
In the standard form of Stayman over 1NT, the responder has a number of options depending on his partner's rebid above:
- If the notrump opener names a major suit and the responder has four cards in that suit, the responder bids three of the notrump bidder's suit [invitational] with 8-9 HCP or four of the notrump bidder's major suit [game] with 10 or more HCP.
- If the notrump bidder bids a major suit in which the responder does not have at least four cards, the responder may bid 2NT [invitational] with 8-9 HCP or 3NT [game] with 10 or more HCP
- If the notrump bidder bids 2 Diamonds, denying a four-card major, responder may bid his five-card major with a call of 2 of his major with 8-9 HCP, or with a call of 3 of his/her major with 10 HCP. This allows notrump bidder to find game in a major with a 5-3 split. Otherwise, opener has the option to retreat to the appropriate notrump contract.
Over these bids, the notrump bidder will:
- with a maximum hand (17 HCP), go to game over an invitational bid
- with 4+ cards in each major suit, corrects to the previously unbid suit in the majors
In the standard form of Stayman over 2NT, the responder has only two normal rebids:
- If the notrump bidder names a major suit and the responder has four cards in that suit, the responder bids 4 of the notrump bidder's suit [game]
- If the notrump bidder names a major suit in which the responder does not have at least 4 cards or bids diamonds to deny a major suit, the responder bids 3NT [game]
- If the notrump bidder has both majors 4 Hearts and 4 Spades, then the notrump bidder corrects to the previously unbid major suit after the 3NT response by partner
In either case, a responder who rebids notrump over a response in a major suit promises 4 cards of the other major suit. Thus, a notrump opener who holds at least 4 cards in each major suit should "correct" by bidding the other major suit at the lowest level. Of course, once a fit is found, responder who has sufficient strength also may bid 4 Clubs [Gerber] or 4 NT[Blackwood] to explore Slam in any of the above sequences. Some partnerships also admit responder's rebids of a major suit that the notrump bidder did not name.
Examples: North's 1NT rebids after - South's 2 Club bid is asking partner, do you have a 4 card major?

2 Diamonds
North denies having a 4 card major suit

2 Hearts
North has 4 Hearts and may have 4 Spades.

2 Spades
North has 4 Spades and denies having 4 Hearts.
Examples: South's rebids after North's 2 Diamonds response.

2 Hearts
South has 4 Spades and 5 Hearts. Invitational with 8-9 points. Non-forcing.

2 Spades
South has 5 Spades and 4 Hearts. Invitational with 8-9 points. Non-forcing.

2 NT
South has an invitational hand with 8-9 points.

3 Hearts
South has 4 Spades and 5 Hearts. Game forcing hand with 10+ points.

3 Spades
South has 5 Spades and 4 Hearts. Game forcing hand with 10+ points.

3 NT
South denies having any possible fit in the majors. Signing off with 10+ points.

4 Hearts
South has 4 Spades and 6 Hearts. Signing off with 10+ points.

4 Spades
South has 6 Spades and 4 Hearts. Signing off with 10+ points.

4 NT
South has 16 points. Quantitative, invites North to bid 6 NT if they have a full 17 points.
Examples: South's rebids after North's 2 Hearts response.

2 Spades
South has 5 Spades and 4 Hearts. Invitational with 8-9 points. Non-forcing.

2 NT
If North does not also have 4 Spades he can pass with 15 pts. or raise to 3 NT with 16-17 pts. With a fit in spades, North should correct to 3 Spades with 15 pts. or 4 Spades with 16-17 pts.

3 Hearts
South has 4 Hearts and an invitational hand with 8-9 points.

4 Hearts
South has 4 Hearts and is signing off with 10+ points.

3 NT
South has 4 Spades with 10+ points. North can choose to pass or bid 4 Spades if also holding 4 Spades.

4 NT
South has 16 points. Quantitative, invites North to bid 6 NT if they have a full 17 points.
Examples: South's rebids after North's 2 Spades response.

2 NT
South does not have a fit in Spades. Invitational with 8-9 points. Non-forcing.

3 Spades
South has 5 Spades. Invitational with 8-9 points. Non-forcing.

3 NT
South signs off with 10+ points and 4 Hearts.

4 Spades
South has 4 Spades. Sign off with 10+ points.

4 NT
South has 16 points. Quantitative, invites North to bid 6 NT if they have a full 17 points.