On my question (Why is 11. .. h6 such a bad move?) someone commented that I should read about the concepts of hooks. One definition that I found was:
A hook is an advanced pawn which can be exploited by the opponent to open lines. (https://chessbookreviews.wordpress.com/2018/07/03/one-small-step/)
I found more examples on the internet that did not explain the concept clearly to me. Do you have further explanations and examples for this concept?
Here's a position from one of my games. I'm playing White versus a master:
[FEN "r2qk1nr/pp2bp2/2p1p2p/3pPnp1/1P6/P1N2N2/2P2PPP/R1BQR1K1 b kq - 0 11"]
[White "D M"]
1... g4
This position isn't great for me, but his pawn storm really isn't all that strong. But imagine if I had a pawn on h3 instead of h2.
[FEN "r2qk1nr/pp2bp2/2p1p2p/3pPnp1/1P6/P1N2N1P/2P2PP1/R1BQR1K1 b kq - 0 1"]
[White "D M"]
1... h5 2. Nd2 g4 *
Now I've got the choice of playing hxg4 or letting him play gxh3. Either way, my king is going to be significantly more exposed than it was in the actual game. But because I didn't have that hook for him to grab, the pawn storm came to nothing and the game was eventually drawn.
Your troubles might stem from the fact that all pawns are hookable, loosely speaking.
I thus define strictly operational: A pawn hook is a pawn in a position that allows the opponent to advance an own pawn, and open a file for its rooks by a capture.
Now consider D.M.'s two positions and the h hook exploited by storming with the g pawn. As soon as the hook "grabs", the opponent has three options:
The first two lead to the desired line opening. Thus, Black might first advance its own h-pawn to h4 so that White can't play h3-h4 (even if this is a pawn sacrifice here, which might be the lesser evil). Compare to the position with Ph2: Advancing to h3 is answered with g3 (uh-oh, g2 stinks, but again, maybe lesser evil), advancing to g3 without reserves leads to the opening of the g line but the rooks stare at a protected pawn, and even if it is annihilated by again playing Ph4, its comrade on g2 still protects the king. Or maybe it typically ends like this: 1...g3 2.fxg3 hxg3 3.h3 and a piece sacrifice on h3 is needed.
Moral: Both positions offer hooks for a pawn storm! Strictly speaking, h3 doesn't create a hook, it moves the hook to an easily exploited position! It's just that the unadulterated f2-g2-h2 position is far more stable against pawn storms.
We can ask how effectively the castled King is guarded by the pawns in front of it. For simplicity of notation consider only short castling, with White on the attack, but all the ideas apply to long castling and Black attackers as well.
At the beginner level, the advice is often given to leave the f7,g7 and h7 pawns where they are. The logic is that this leaves the attacker with few avenues of approach. They can play Qh5 and Ng5 for example but often this can be met simply by Nf6. Successful attacks usually involve bringing more attackers into play than there are defenders. This often requires opening lines for Rooks and Bishops. For example if Black has played h6, then g5 can open the g-file (in case of gxh) or the h-file (in case of ...hxg), or the c1h6 or b1h7 diagonals This will not work if Black is able to play ..h5, so White will often try to control that square first. Similarly, if Black has played ..g6, the line opener will be f5 or h5. The Pawn on h6 or g6 is sometimes referred to as a "hook". The prelude to attacking play often centers around creating a hook. If ..Nf6 is not available then Qh5 and Ng5 may force ..h6. Black may play to prevent these manoeuvres or to create stronger counterthreats elsewhere
