Weak white/black squares

I notice that good players often point out that a position will have weak white or black squares. I understand this a little bit, but I still have questions as to how we know there is a weakness and more importantly when and how can this weakness be exploited. I wish I could say I have the answers to these questions, but I'm pretty certain that it comces down to each position being unique. Sometimes the weak color can be used  and sometimes it can't and the specific way it can be used depends on the other weaknesses in the position.

The best I can do is annotate some examples from my own games where a weak color was utilized to win the game. 

 In the first example, white gives up the light squared bishop early in the game and later weak white squares become jumping off points for black's pieces.

In the second example, black has given up his kingside fianchetto and a mating attack is delivered simply on the basis of the weak dark squares around the king.

The third example is also a mating attack on the dark squares where the fianchettoed bishop has been eliminated. This time we'll look at the whole game: