How to Identify Weak Squares

How do you go about identifying weak squares? I there a precise definition of what a weak square is?

A weak pawn or weak square is a pawn or square that cannot be defended by another pawn.

If you have a fiancetto on g2, are f3 and h3 still considered weak squares? They are protected by the Bishop.

What about with pawns on f2, g2 and h2. Does that mean squares f4, g4 and h4 are not considered weak squares because in the future they could be defended by a pawn?

Are we saying that a square is weak if you had a Knight, Bishop, Queen and Rook all pointing to that square, if it can never have a pawn attacking it?

If you have to use a piece to defend a weak pawn or square?  Then yes it is weak because you are using a piece to do something that a pawn is not able to do.

The squares around a fianchetto are typically safe because of the strong Bishop occupying g2/b2/b7/g7. However, if this (g2) Bishop is traded off, then the squares f3 and h3 and even g2 become weak and vulnerable to infiltration, especially if White lacks an e-pawn and Black has a light-squared bishop.

Are you saying that if the Bishop is not traded off, then the squares are not weak?

Weak squares are holes in the pawn structure where an enemi piece can install itself.
"If you have a fiancetto on g2, are f3 and h3 still considered weak squares? They are protected by the Bishop" After the bishop is traded off those squares are weak.
"What about with pawns on f2, g2 and h2. Does that mean squares f4, g4 and h4 are not considered weak squares because in the future they could be defended by a pawn?" Pawns on f2, g2, h2 are optimal: no weak squares, though the first rank may be weak if an enemi rook lands there.

For the most part. Although they are by definition weak, in practice those squares are well covered and are hard to install pieces on. Often in the Sicilian Dragon, White tries to trade off his dark-squared Bishop for Black's fianchettoed one, in order to remove the defender of the dark squares, making it easier for White's assault to succeed.

If for the most part they are not weak, why would they be defined as weak? Do you see what I am getting at here? Is it a case that when we say weak squares or not weak squares, in fact our binary thinking is misleading us? Instead, there is a continuum of weakness.

They are considered weak because you are using a piece to do something a pawn could do, but cant.

Right. You have to look at each position carefully. There are many situations where a "bad" Bishop becomes very useful and strong. While labels like "weak squares" and "good" or "bad" Bishops can be useful, they can also become a crutch that prevents a player from seeing the truth of the position.

Weak squares are a static trait of a pawn structure. To identify weak squares remove all pieces from the board and just leave the pawns and kings. Now look which squares are accessible to the enemi king. Those are weak squares.

I've thought of two additional scenarios that I am unclear on.

1. If you have a fianchetto structure with pawns on f2, g3 and h2, and a Bishop on h3, is h3 still considered a weak square, even though it has a piece on it?

2. What about if you have pawns on e2, f4, g4, and h4...does that mean g3 is considered a weak square, or is that not a weak square since it is behind a phalanx of pawns?

#14
1. Yes, it is weak, as a black piece or the black king can invade there once the defender is exchanged.
2. No, g3 is not weak as it is behind the phalanx of pawns as you say, so the black king has no entry.