You (S) are responder with the following hand.

The bidding so far has gone : (N) 1♣ - (you) 1♥ - 1♠ - you ?

1. With 11-12 points you are too strong to rebid . . . . . (showing 6-. . . points)

2. Neither should you jump rebid . . . . . as that shows a . .-card suit

3. Your best bet would normally be 2NT, but that is risky without a . . . . stopper.

The fourth suit forcing convention provides a solution to such type of problems.
With a strong response hand (. . . points) where a Game contract might be on, but no clear rebid is available, Responder bids the 4th (as yet unbid) suit.   Simply respond (N) 1C - 1H : 1S - you 2D

After the 4th suit, Opener must . . .. He also must . . . . . . after Responder's next bid, if Responder bids below Game. The Responder however may . . . . . after an initial weak reply by the Opener.

The 4th suit forcing applies in all cases except in natural progressions like :   . . . . . . . . . . . . .
Here the 1♠ bid is natural, showing a 4+ card spades suit and 6+ points.

If you do wish to make a fourth suit forcing bid in such case, bid . . . instead :. . . . . . . . . . . . . . . .

Answers

The 4th suit forcing applies in all cases except in natural progressions like :   1♣ - 1♦ - 1♥ - 1♠
Here the 1♠ bid is natural, showing a . . . . card spades suit and . . . . points.

If you do wish to make a fourth suit forcing bid in such case, bid . . . . . instead :   1♣ - 1♦ - 1♥ - . . . . . .

In rare cases you may actually hold a 4-card or 5-card 4th suit.
With 4 cards in the 4th suit (or with 2 or 3 cards including a stopper), don't bid that suit but bid . . . . . (with 11-12 points) or . . . . . (with 13+ points).   For example :

Partner opens the bidding : 1♣ - 1♥ - 1♠ - you . . . . .

Note that Opener will bid 3♥ over your . . . . , if he has . . . . . . . . . . . . for your Hearts suit.

With a 5-5 or 6-5 suit holding, . . . . . . your second suit (so in fact . . . . . . . . . . . over the 4th suit forcing bid).   For example :

Partner opens the bidding : 1♣ - 1♥ - 1♠ - you . . . . . .

Note that with 3-card support for either your Hearts or Diamonds Opener with raise that suit. If Opener does not do that he must have a good holding in . . . . . and bid . . . . . .

Answers

After Responder's 4th bid forcing bid Opener has the following reply options. In order of their priority :

1. Show . . . . . . . . . . . . . . . . . . . for Responder's (likely) 5-card suit.

2. Bid . . . . with at least one . . . . . . . in the . . . . suit

3. Raise the . . . . . . suit.
   a - If Opener could genuinely hold the . . . . suit, his raise shows a . . . . . . . . . . . . . .
   b - If Openere earlier . . . . . . holding the 4th suit, he is showing a . . . . . hand (. . . points) but with . . . . . . in the 4th suit.

4. Failing any of the above, he rebids . . . . . . . . . .

If Responder's long suit is a . . . . . suit Opener's priorities 1 and 2 (above) are reversed.
Here follow some typical examples.

Example 1	Opener (N) ♠ - K Q 7 2 ♥ - 6 4 ♦ - A 9 ♣ - K Q 9 6 3		Responder (S) ♠ - A 8 ♥ - K 9 8 5 3 ♦ - 7 4 3 ♣ - A 8 4		Comment After Opener's weak reply of . . . , Responder is not strong enough to bid . . . .
	Bidding : (N) 1C -

Example 2	Opener (N) ♠ - K Q 7 2 ♥ - 6 4 ♦ - A J 10 ♣ - K Q 9 6		Responder (S) ♠ - A 8 ♥ - K 9 8 5 3 ♦ - 7 4 3 ♣ - A 8 4		Comment With 15 points and the . . . . . suit well stopped Opener has the strength to bid . . . . . ..
	Bidding : (N) 1C -

Example 3	Opener (N) ♠ - K Q 7 2 ♥ - A 6 4 ♦ - 9 ♣ - K Q 9 6 3		Responder (S) ♠ - A 8 ♥ - K 9 8 5 3 ♦ - 7 4 3 ♣ - A 8 4		Comment With good . . . .-card trump support for Responders Heart suit and the . . . . . . Diamond, Opener bids . . . . . .
	Bidding : (N) 1C -

Example 4	Opener (N) ♠ - K Q 7 2 ♥ - J 6 4 ♦ - 9 ♣ - K Q J 9 6 3		Responder (S) ♠ - A 8 ♥ - A K 9 8 5 ♦ - 7 4 3 ♣ - A 8 4		Comment With . . . -card trump support Opener can reply in Hearts but is . . . . bid . . . . . Responder . . . . . . . . . . . . .
	Bidding : (N) 1C -

Example 5	Opener (N) ♠ - K Q 7 2 ♥ - 6 4 ♦ - 10 9 ♣ - A K Q 9 3		Responder (S) ♠ - A 8 ♥ - K 9 8 5 3 ♦ - 7 4 3 ♣ - A 8 4		Comment With no . . . . . . . . . for Responders Heart suit and no . . . . . . . . Opener rebids . . . . . ..
	Bidding : (N) 1C -

Answers

When Opener rebids the suit opened and Responder changes suit, Opener has also the opportunity to make a 4th suit forcing bid. There is no need to be . . . . . . , Opener can make such bid with a . . . . . . Opening hand (. . . . . points).   He holds for example the hand shown below, and the bidding goes : 1♦ - 1♠ - 1♦ - 2♥ - ?

A 4th suit forcing bid is very useful here 1♦ - 1♠ - 2♦ - 2♥ - 3♣ !
If Responder replies . . . . , showing the . . . . . stopped, 3NT is likely. If he replies with Diamonds Opener can always bid . . . . . . . , as a . . . . . fit with his useful . . . . . will probably be worth a try for . . . . . .

Here another 4th suit opportunity for the Opener. This time it is the Responder who has bid the same suit twice. Opener holds the strong hand below, while the bidding goes : 1♦ - 1♥ - 3♣ - 3♥ - ?

By bidding : 1♦ - 1♥ - 3♣ - 3♥ - 3♠   the Opener . . . . . . support for partner's Hearts and also . . . . . a stopper in Spades.

Answers

Responder's reply to a 4th suit forcing bid are similar to those of the Opener's replies.

1. Bid . . . . . with a stopper in the 4th suit

2. Give . . . . . . for Opener's suit with 3-card support,
   or support with . . . . . . support (!) if Opener has shown a 5- card major.
   (With a strong hand . . . . . Opener's suit, showing interest in . . . . .)

3. Rebid Responder's own suit if he holds . . . . . . . .

Example 1	Opener (N) ♠ - K 5 ♥ - Q 6 ♦ - A K 10 9 4 3 ♣ - 7 4 2		Responder (S) ♠ - Q J 10 7 2 ♥ - K 10 8 4 ♦ - 8 ♣ - A J 9		Comment With the . . . . . stoppers South bids . . . .
	Bidding : (N) 1D -

Example 2	Opener (N) ♠ - K 5 ♥ - Q 6 ♦ - A K 10 9 4 3 ♣ - 7 4 2		Responder (S) ♠ - Q J 10 7 2 ♥ - A K 10 4 ♦ - Q J 5 ♣ -		Comment As a second bid S prefers to show . . . . . . . rather than his . . . . . . . . . support, hoping a . . . . .contract might be on. After N's 4th suit bid, South is sure a . . . . . . is on.
	Bidding : (N) 1D -

Lateral thinking !
With his 4th suit forcing bid, North denies a Club stopper, he also can only hold . . . . points at the most in his Diamond suit (South holds the other . . . points). Therefore North must hold at least . . . . or more in the majors. This convinces South that . . . . . . .is a good bet. Declarer would probably raise to . . . . . with a strong, rather than a . . . . . . hand.

Answers