Fourth suit  focing is one of those strange conventions which experts can pontificate about for hours but which scare inexperienced players rigid. Maybe it is because the concepts are not suitable for beginner classes so are not picked up early in your bridge career but at the same time it is not easily self taught like some conventions.  Of course, once you have been playing for a few years, no bridge player is going to admit openly something like "I don't really understand the purpose or ramifications of fourth suit forcing (FSF)". If you are one of those people, I promise that I won't tell anyone if  you email me a question!! One useful attribute of fourth suit forcing is that it is at least well named which should help make it easy to remember. It usually involves the bid of the last unbid suit in an unopposed auction where you do not want the auction to die.

There are two main situations when the convention is useful:

1.  You have enough points to proceed towards game but have no clear cut bid. Maybe your own suit is not worth a rebid and you don't like partner's suits yet you do not hold a stopper in the unbid suit so cannot safely bid no-trumps.
The answer is often to bid the fourth suit to get more information from partner. Maybe they will finally support your suit (I know, its like getting blood out of a stone isn't it!!) or maybe they will have the required stop and bid no-trumps.

For example, you hold: ªAJ432 ©K95¨J32§Q8. The bidding begins:
 
 

NORTH	PARTNER	SOUTH	YOU
	1 Club	Pass	1 Spade
Pass	2 hearts	Pass	?

What do you bid?

Your spades are not worth a rebid and bidding no trumps from your side of the table does not look sound. You cannot really support hearts or clubs yet but game seems certain somewhere after partner's reverse, so what can you do?  The answer is to bid the fourth suit (three diamonds here) as a relay asking for more information. All being well, partner's next bid will help you to identify the right game.

2. You are certain that game is on in one of partner's suits but you do not want to just bid game immediately because it wastes bidding space that can be used to investigate a possible slam.
The answer might be to set up a forcing sequence by bidding the fourth suit and then bidding partner's suit. As long as partner has read this article too, they will know that this sequence shows slam interest and is certainly forcing to game.

What do you bid?
 

For example, you hold: ªAK54 ©AT9¨K9§AT86. The bidding begins:
 
 

NORTH	PARTNER	SOUTH	YOU
	1 Diamond	Pass	1 Spade
Pass	2 Clubs	Pass	?

What do you bid?

Once more game is certain and a slam in clubs is a distinct possibility. The best way forward is to bid two hearts (FSF).
If partner bids spades now (implying a heart shortage) or 2NT (implying some help in hearts) the a slam is very likely and you can continue with  3 Clubs  (forcing of course!!).

If you are playing FSF, then you still have lots of issues to discuss with partner. These include:

(a) What do you bid if you have length in the fourth suit and want to bid it naturally?  For example, you hold:

For example, you hold: ªAK7654 ©AT987 ¨9 § Q . The bidding begins:
 
 

NORTH	PARTNER	SOUTH	YOU
	1 Diamond	Pass	1 Spade
Pass	2 Clubs	Pass	?

What do you bid?  My suggestion would be to play a jump in the fourth suit (3 Hearts here) as natural and showing this type of two suiter.

(b) How far is fourth suit forcing. Many players play a fourth suit forcing bid at the two level as forcing only as far as two no-trumps and fourth suit forcing bids at the three level as forcing to game. However there are many complications in subsequent auctions after two level fourth suit forcing bids and many players (usually optimists like me) have decided to play all FSF sequences as forcing to game. This certainly cuts down on arguments and partnership divorces!

You will also need to discuss things like: What does a raise of the fourth suit mean? What do jump responses mean?
Oh and finally, don't forget that you can have a fourth suit forcing sequence at the one level!!

Happy New Year.