STAYMAN
Many
years ago Sam Stayman came up with an idea that if partner had
opened 1NT then it was not normally a good idea to play in Clubs.
He realised that it was more important that you should have a way to
ask partner if they had four Hearts or four Spades.
He
introduced the idea that if partner opened 1NT that the 2♣ response was a totally artificial bid that
asked partner if they had either a four card Heart suit, a four card Spade suit
or both.
OPENER RESPONDER
1NT 2♣
12-14 Do you
have a four card major?
(This
says nothing about Clubs)
ANSWERS
2♦ No,
neither. This says nothing about Diamonds.
2♥ I have Hearts,
I may have Spades
2♠ I
have four Spades, I do not have four Hearts
IN PRINCIPLE you need 11+ HCPs to use Stayman. The reason is that if partner does
not have four Hearts or four Spades they will reply 2♦.
You may not want to play in Diamonds so you have to hold enough HCPs to bid
2NT, or more.
ONLY USE STAYMAN IF YOU HAVE A FOUR CARD MAJOR, OR TWO

There will of course be the odd exception!!!!