A game in Major is always a priority in modern bridge. In 1NT balanced opening, there is confirmation that the opening hand has at least one Major with 3+ cards and 15-17 HCP.  When responder has a 4+ cards Major and 8+ HCP, a convention called Stayman can be used, quizzing opening partner, if he too, has a 4+ cards MAJOR? If yes, disclose which one.

Responder will exercise Stayman with artificial bid 2!c 

The theme to make opener the declarer is the basic reason we use Stayman. By doing so, the stronger hand with opener remains hidden to opponents and they do not get to see his cards as dummy.

There are just 3 options to opener in Stayman

• 2!d None
• 2!h 4+ hearts
• 2!s 4+ spades.

Action over 2!d negative relay

2!h or 2!s as next bid is invitational hand with 5+ cards. Responder here expects opener to rebid 3 or 4 of the same major, showing 3+ card support and decision on game or part score, declare.

2NT response is invitational for a NO Trump game. 3NT is jump to game with 10+ HCP.

3!c or 3!d new suit is game forcing. Indicates 10+ points hand.

3!h or 3!s is SMOLEN . Responder has 4 of the bid major and 5 of the other major with game forcing hand.

4NT is quantitative invite to slam. Playing No Trump.

Action over 2!h or 2!s positive relay

On 2!h opener relay, responder may have intended !s and is sitting with 5+ cards. His next bid should be 2!s

The above exception is rare. For all other opener’s affirmative relays, responder’s next bid over 2!h or 2!s will be:

• 3 of the same Major to show invitational hand 8-9 HCP
• 2NT if responder has the other Major with just 4 cards and invitational hand
• 3NT is jump to game with 10+ HCP. Responder has other Major.
• 4 of the same Major to jump to game, generally, 10+ HCP
• 3 of the other Major is Slam Investigation. Shows game force in play and trump suit agreed (opener’s bid of the Major is trump suit).
  • 4 of the agreed trump suit is sign off
  • 4 of other suits is 1^st or 2^nd trick control. Basically, level 2 Cue Bids. 3014 Roman Keycards Blackwood Convention via 4NT, may follow later.
• 4NT is quantitative invite to 6NT.

Important Notes :

• Restrict use of Stayman with minimum strength of 8+ HCP because It can result in 2NT bid. 
• After opener’s 1NT if opponent interferes with Double,  Stayman can still be used but it will be rare as opener+doubler have consumed 30+ HCP. Remember, Stayman mandates 8+ HCP for its application.
• Cappellette convention bid by overcalled can block Stayman space for bidding. ACBL recommends that a Cue bid should be used to signal Stayman. That means:

1NT-2!c-3!c/double-    is Stayman

1NT-2!h-3!h-                is Stayman

1NT-2!s-3!s-                   is Stayman

• BBO robots follow GIB convention card and use Double as Stayman when 2!c bid is taken up by Cappellette overcall.