I'm really struggling to understand this move to be honest. Even after carefully reading a similar question posted here, I still just don't get it and, more importantly, when it's good to play the f6 break. I apologize if that seems stupid.
Can someone explain it in very clear and simple terms for me please? Is it just for making a semi-open file for the rook? Getting rid of white's e pawn? I'm a little unsure about this topic.
The f6 break is a key idea in the French defense, and the point is mainly to add more pressure to White's center. In the French, one basic line of thought is the following:
If black manages to complete steps 1-3 outlined above, without significant material losses or a serious weakening of the king's position, step 4 will indeed often be possible to accomplish.
Let us examine the move f6 in view of the steps above. If White has a pawn on e5 and black plays ...f6, it's possible to
a) If Black hasn't castled, it most likely means that Black will have to respond to this with ...gxf6. Black now typically has pawns on e6 and on f6. It is not hard to see that Black can have plans to push ...e5 in the near future, and if the pawn capture on f6 hasn't left Black's king open to direct attack, it's possible that Black will achieve steps 2-3 outlined above shortly.
If Black has castled, on the other hand, more options than ...gxf6 will be available. Often either a knight, bishop or a rook could also take on f6 in this case. In case of rook capture, Black has a semi-open f-file for his/her rook. Taking with a bishop adds more pressure on the a1-h8 diagonal. Taking with a knight adds possibilities to play ...e5 to free the black bishop on c8 in some cases. It is clear that the ...f6 break by Black has given many possibilities for future plans.
One more note: If White takes the pawn on f6, the h2-b8 diagonal will be ripe for the black bishop to occupy, often coupled with a queen on c7. This is sometimes very unpleasant for White.
b) If White protects the pawn, Black has some other options with ...f6 played. If White has played f4, Black could sometimes take on e5, and if White recaptures with the f-pawn, it can in some cases be possible to play ...Qh4+ for some concrete tactical purpose. Other times Black can be perfectly happy with just trying to take over the f-file and pressure White's position that way. If White recaptures with the d4 pawn instead of the f-pawn, Black has the option to open the diagonal a7-g1 with ...c4, or play ...d4 and just try to break once again in the center, to activate his/her pieces.
If White has played f4, and it's not good for Black to take on e5, Black can wait, and try to maneouver the c8 bishop to g6 via Bc8-d7-e8-g6. This is a standard plan in the French defense to activate that light squared bishop. Or Black can lock the center with ...f5 in some cases, to stop White from attacking the black king. In rare cases, after White has played f4, Black can even try to play ...g5, to again just try to break up White's center. This can be very risky, so it's not often the first idea Black thinks of, but it should never be forgotten, as it can recieve a great pay-off if well executed.
If White guards the e5 pawn with Bf4, the g5 break is more natural, and Black can even try to go for a kingside pawn storm in some cases. Again, it has to be well executed, as it can easily expose Black's king. Otherwise it's more typical for black to keep the tension in the center, and let White make the big decision to alter the status quo. However, at every move, White has to be wary of possible alterations of the center. The same is usually true if White defends e5 with another piece.
c) This option is very rare, and can only be considered if White manages to create an enormous treat elsewhere on the board that black needs to deal with immediately. If this is the case, the ...f6 break may be a bad idea. Otherwise, if White ignores the ...f6 break, Black can usually just take on e5, and normally having a knight on c6 and a queen on c7 (and maybe even a knight on d7 in some cases), this can mean that black simply wins a pawn.
This reply got much longer than I originally had intended it to be, but I feel like most of the reasons why Black may consider playing ...f6 in the French defense are in here. Remember that I have not included any concrete examples here, and that it all depends on the position. If ...f6 is an obvious blunder, for some reason I failed to mention here, it should of course not be played.
TL;DR: ...f6 is about challenging White's control over the center, and trying to open up the position for Black's pieces.
f6 is a thematic idea in positions (such as the advanced French) with locked pawns. The theme is the "pawn break".
Pawn breaks are most often done with the c or f pawns because the central d and e pawns are the most likely to become locked after an advance. There are three common motives:
So f6 in this context can serve many purposes. In light of options like c5, which has the virtue of not weakening your kingside, it might be worth not rushing into the idea.
It attacks white's pawn centre and cramping e5 pawn and opens up the f6 square if it is taken or opens up the rook's line if black takes on e5.
Often when black does not try to get play in the center and/or kingside, he can get slowly crushed. For example:
[FEN ""]
1. e4 e6 2. d4 d5 3. Nd2 Nf6 4. e5 Nfd7 5. Bd3 c5 6. c3 Nc6 7. Ndf3 Qb6 8. Ne2 Be7 9. O-O cxd4 10. cxd4 Nb4 11. Bb1 O-O 12. a3 Nc6 13. Qc2 g6 14. Bh6 *
The ...f6 break can be very useful in advance variations of the French because it saves Black from being completely passive. In playing the French, Black makes a fundamental trade-off of giving White space in exchange for defensive solidity; however, Black needs to counterattack otherwise White will steamroll.
The main feature of White in the Advance is the pawn chain c3, d4, e5. That chain gives White space and freedom of movement. Black's main strategy is to attack the chain and if Black can undermine White' structure, White's position will be fragile. It is definitely not for use in every game, but it can be really handy.
The most essential counterattacking pawn move is ...c5, attacking the pawn chain at d4. This will also give Black some space to develop other pieces. ...f6 should happen a bit later, and lets Black attack the chain at two points (d4 and e5). If White takes, it leaves Black with a structural weakness in the pawn at e6, but Black eliminates a lot of White's early advantage while gaining more piece activity.
In my experience, the ...f6 break has to be timed right and the c8 bishop still needs to be at c8 or d7 to protect the e6 pawn (b/c that bishop usually doesn't do so much in the opening anyway.
The short answer is: it forces exchange of a center pawn for a non-center pawn. If White ever captures exf6, Black's gxf6 gets the e pawn for a g pawn, or if Black captures f6 with a piece, gets the e pawn for the f pawn. If White declines exf6 then Black plays fxe5; if White recaptures dxe5 then Black gets a d pawn for the f pawn, or if White recaptures with a piece, the e pawn for the f pawn. In all cases, a slight center advantage toward Black in the pawn exchange.
The force is of course because White cannot push e5 to e6 in the French.
Also, this assumes that White cannot respond to f6 with f4 -- make sure not to play f6 unless White has that N (or other piece) on f3.
Black has two main breaks in the French
