This bid is a convention.
The Stayman convention is a standard response to a natural 1NT or 2NT opening, developed by Samuel Stayman in 1945. In its most basic form, it is an asking bid, asking partner to bid a 4-card major suit or 2♦.
Usage after 1NT opening
- 2♦: no 4-card major
- 2♥: 4 ♥s, may have 4 ♠s. (the original version prefers 2♠ in case of 4-4 in majors)
- 2♠: 4 ♠s, no 4 ♥s.
For a maximum hand with good fit, the following may be used as extensions:
- 2NT: 5 ♦s and a major, non-minimum:
- 3♣: 5 ♣s and a major, non-minimum:
- 3♦: asks for major;
- 3♦: both majors, maximum:
- 3♥: 5 ♥s, maximum;
- 3♠: 5 ♠s, maximum.
- 2♥: 5 ♥s and 4 ♠s. May be non-forcing or forcing one round depending on the variant used.
- 2♠: 5 ♠s and 4 ♥s. May be non-forcing or forcing one round depending on the variant used.
- 2NT: invitational to 3NT, denies a fit.
- 3♣/3♦: Originally played as weak and must be passed, but now commonly played as game forcing since weak minor hands start with 2♠ when Jacoby transfers are in use, details depends on partnership agreement.
- 3♥/3♠ (after 2♦): Game forcing with 5-4 in the majors in the non-forcing variant. The 5-card major is bid unless Smolen transfer is used.
- 3♠ (after 2♥): Game forcing with 4 ♠s and less than 4 ♥s in the non-forcing variant. Raise to 4♠ or return back to 3NT.
- 3NT: sign off, denies a fit.
- raise to the 3-level: invitational, confirms a fit.
- raise to the 4-level: sign-off, confirms a fit.
There are many conventions regarding the rebids. See Category:Stayman for more.
The following lists variants which the usage of the 2♣ asking bid differs from the standard usage (invitational+ and with a 4-card major), but not the continuation afterwards.
 In this variant, 2♣ does not promise invitational values. Instead, it may perform as a weak takeout when holding a 3 suited hand short in clubs. Responder passes any opener rebids, with the likelihood of having a fit in the suit opener bid. At least 7-card fit can be found with the exception of 3=3=2=5 distribution. On the other hand, a 2♦ contract is likely to be less costly than a 1NT in which the opponents have a majority of the high card points.
 This is an extension to Garbage Stayman, which can be used in all hands without invitational values and 4 cards in both majors. After bidding 2♣, pass any 2♥ or 2♠ response, but instead rebid 2♥ over 2♦. In this case, 2♥ specifies that the hand is weak and asks opener to bid his 3-card ♠, but pass with 3-card ♥. At least 7-card fit is guaranteed.
 This variation may be used when the NT opening allows a 5-card major. It is mainly used after 2NT opening (however usage after 1NT opening is also possible). After 2NT, a bid of 3♣ guarantees game-going value and asks for a 5-card major:
- 3♦: have an unspecified 4-card major.
- 3♥/3♠: have the named 5-card major. Responder raises it or return back to 3NT.
- 3NT: have no 4-card major. To play.
 When not using Jacoby transfers (e.g. over a weak 1NT opening), 2♦ may be employed as the game-forcing variant of Stayman and 2♣ be the non-forcing variant. Opener rebids 2NT if holding no 4-card major.
When the sequence 1NT-2NT or 2NT-3NT is used as a convention, responder bids Stayman even without a four card major. In this case, the 2♠ bid by responder in the sequence 1NT-2♣-2♥-2♠ is used as a check-back if opener holds 4 ♠s.
This is a variant of Stayman used after a NT response intended to keep the strong hand as the declarer, commonly used by Precision players. After 1X - 1NT, 2♣ is transfer Stayman by opener, and is responded: 2♦: 4+ ♥s; 2♥: 4+ ♠s; 2NT: no 4-card major.