When partner opens one of a suit they promise something in the region of 12 - 20 HCP (high card points) Their second bid (a re-bid) will attempt to define more fully exactly where they stand both in terms of their overall shape and point count.
This means that you, as "responder" must keep the bidding alive with any hand worth 6 or more HCP. This is because if - as you wish, hope and pray - partner has the magical 20 HCP, then the partnership will have between both of you the even more magical 26 HCP and this should be enough to make game likely. If, on the other hand, partner has some grisly 12 count, then you will let the bidding die in a safe - you trust! - part-score you mutually arrive at.
When partner opens one NT they promise exactly 12 - 14 HCP, no more, no less. Now you as responder have a much clearer idea of what the partnership can achieve. Consequently, you know that unless you have at least 11 HCP, game will not be likely (14 + 11 = 25) So, if you have less than 11 HCP, knowing game is not on, you can pass. At the same time, you are also able to judge whether or not 1NT is a "good" contract. This will happen when you have 0 - 10 HCP (game not on) but your shape is such that you need to tell partner of your fears. Because you can't easily tell partner about an unbalanced hand with a minor suit (2C=Stayman; 2D =Transfer!), you should forget it and still pass, but if you are unbalanced with a long (5+) major suit you should first transfer (2D or 2H), then pass and trust the partnership is in a better place.
If your hand really, really is pretty dire but contains 6+ minor then you can get out of the mire by bidding 2S! this is a transfer to 3C which you can correct to 3D if that is your suit.
Not So Basic: Overcalling
When the opposition "open" the bidding, the bid you make will be an "overcall". Overcall bids have more than one function: They might:
- Tell your partner your suit
- Suggest a lead
- Disrupt the opposition bidding
- Find a sacrifice
(1D)-pass-(1S)- ?? and you hold:
To bid or not to bid: that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune,
Or to take arms against a sea of troubles,
And, overcalling, end them?
Your instinct should probably veer you towards overcalling but there are traps for the unwary here. It’s not just about the points – but where they are. The king of diamonds looks dead and you have no surprises in the spade suit. Suddenly the 13 count doesn’t look quite as good as it did – let’s call it 10 in reality. And it’s flat as a pancake. Added to that both opponents are as yet unlimited - ie partner could have a round zero over there and all you do by overcalling is tell the opposition exactly how to play the hand. That said, there’s nothing "wrong" with a bid of 2H (it gets in their way & suggests a lead), but, vulnerable, it looks an iffy prospect.
Now look at this:
This hand, in contrast to the one above, has exactly the same high cards but in different places. Now that king is working; the ace, too - 'connected honours' reinforce each other. The singleton gives the hand extra possibilities as well. Now an overcall of 2H looks practically mandatory at any vulnerability. Of course it could still all go alarmingly haywire, but at least this time you had better reason to get involved and you may even get a plus score:
…'tis a consummation
Devoutly to be wish'd…