The fight against mobile central pawns
How to break up a strong central pawn duo
How can you fight the opponent's mobile central pawns? Let's look at a few typical methods, each suited to a different kind of position.
A flank pawn break
Consider the case where White has reached the "ideal" pawn setup — pawns on e4 and d4 — while Black lacks an adequate pawn screen: only one pawn on the central files, or none at all.
How can Black break up White's strong pawn position? After the move c7-c5 (assuming the c5 square is defended), White can answer d4-d5, getting a strong passed pawn. If for some reason White cannot meet c7-c5 with d4-d5, White's pawn position becomes weaker — for example, after the trade d4xc5.
Now consider a strike with the other flank pawn: f7-f5. Here White keeps the position intact by answering f2-f3. But if White cannot hold the pawn on e4, Black gains positional benefits: the weakness of the d4 pawn and control of the d5 square.