[kriegel]

Here's the situation: your partner opens the bidding (yay!) and you respond. He rebids, and it's your turn to call. Do you know what your bids mean now?

There are a couple of easy guidelines that responder can follow with his rebids. In a simple auction that begins with 1x - 1y and opener rebids his own suit or a new suit, there are three basic rules assuming natural bidding methods:
1. A new suit is forcing.
2. 1NT or an old suit at the 2-level shows 6-10 points.
3. 2NT or an old suit at the 3-level shows 11-12 points.
A "new suit" is simply a suit that hasn't been bid before, and an "old suit" is a suit that either opener or responder has bid already.

Here are a few examples:
1♣ - 1♥
1♠
........1NT shows 6-10 points
........2♣, an old suit (opener's), shows 6-10 points and 4+ clubs (usually)
........2♦, a new suit, shows 11+ points OR is a convention like 4th suit forcing
........2♥ shows 6-10 points and 6+ hearts (responder's suit)
........2♠ shows 6-10 points and 4 spades
........2NT shows 11-12 points and a diamond stopper
........3♣ 11-12 points, usually 5+ clubs
........3♦ I don't want to get into a jump in a new suit
........3♥ 11-12 points, 6+ hearts
........3♠ 11-12 points, 4 spades

1♦ - 1♠
2♦
........2♥/3♣ new suit, forcing
........2♠ 6-10, 6+ spades
........2NT 11-12, balanced
........3♦ 11-12, 4+ diamonds
........3♠ 11-12, 6+ spades

1♦ - 1♥
2♣
........2♦ 6-10, 2+ diamonds. This is a preference, which doesn't promise real support just a better hand for diamonds than clubs.
........2♥ 6-10, 6+ hearts
........2♠ new suit, forcing
........2NT 11-12, hearts stopped
........3♣ 11-12*, 4+ clubs
........3♦ 11-12, 4+ diamonds
........3♥ 11-12, 6+ hearts

*OK, this is an exception to the 11-12 guideline. Due to space constraints, this needs to have a wider range (like 8/9-12), but as a beginner, just treat it as 11-12. The proper name for this sequence is a courtesy raise.

Things are more complicated over a 1NT rebid. Because opener has so narrowly defined his hand (12-14 balanced), responder's new suits are non-forcing. This is one of the only sequences where new suits by responder are not forcing. Almost everyone uses some kind of checkback, such as New Minor Forcing, to gain a forcing bid over a 1NT rebid. Here is an example using only the "natural" meaning of the bids:

1♦ - 1♠
1NT
........2♣ 6-10 points, 5+ spades, 4+ clubs, non-forcing (opener passes or corrects to 2♠)
........2♦ 6-10 points, 4+ diamonds
........2♥ 6-10, 5+ spades, 4+ hearts, non-forcing (opener passes or corrects)
........2♠ 6-10, 5+ spades
........2NT 11-12
........3♦ 11-12, 4+ diamonds
........3♠ 11-12, 6+ spades

Using New Minor Forcing
........2♣ New Minor Forcing, 11+ points, asking for more information
........2♦ same
........2♥ same. This sequence remains pass/correct showing a weak hand.
........2♠ same
Higher bids also remain the same.

It's up to your partnership to decide what to do with jumps in new suits over a 1NT rebid (1♦ - 1♠; 1NT - 3♥).

[S2000magic]

 kriegel, on 2012-June-03, 17:45, said:

Here's the situation: your partner opens the bidding (yay!) and you respond. He rebids, and it's your turn to call. Do you know what your bids mean now?

There are a couple of easy guidelines that responder can follow with his rebids. In a simple auction that begins with 1x - 1y and opener rebids his own suit or a new suit, there are three basic rules assuming natural bidding methods:
1. A new suit is forcing.
2. 1NT or an old suit at the 2-level shows 6-10 points.
3. 2NT or an old suit at the 3-level shows 11-12 points.
A "new suit" is simply a suit that hasn't been bid before, and an "old suit" is a suit that either opener or responder has bid already.

Here are a few examples:
1♣ - 1♥
1♠
........2♦, a new suit, shows 11+ points OR is a convention like 4th suit forcing (emphasis added)

Although people commonly refer to the convention as 4^th suit forcing, a more descriptive name is 4^th suit forcing and artificial; the key here is that, using this convention, 2♦ might not show a biddable diamond suit; it could be, say, a weak doubleton, and responder simply wants opener to describe his hand better. (In particular, opener should bid notrump only if he has a secure stopper in diamonds; he shouldn't rely on responder to have a stopper.)

Treating 2♦ as forcing here is standard, not conventional; the convention is that 2♦ might not show a true (biddable) diamond suit; i.e., that 2♦ might be artificial.

 kriegel, on 2012-June-03, 17:45, said:

1♦ - 1♥
2♣
........2♠ new suit, forcing

Another case of 4^th suit forcing and artificial: here 2♠ might not show a biddable spade suit. (Note that there's no reason to introduce a 4-card spade suit here; if opener had had 4 spades, he would have rebid 1♠, not 2♣, so if spades shows a real suit it should be a 5-carder.)