Removing the Defender
This move removes the defender of the knight on c3. But in this case the theme goes beyond just winning two pieces for a rook. The fianchettoed bishop on g7 was also the pride and joy of Black's game.
This kind of move isn't so hard to find, especially when you can foresee that it doesn't sacrifice material. In fact, it wins material by force! The forcing nature of the combination makes these kinds of moves possible to calculate.
Although this walks into a possible discovered check later, it is the only way to be certain of getting both minor pieces for the rook. Hiding on h1 or h2 loses more material after 24…. Kxg7.
Calculating a series of captures accurately takes practice. That's why one of the best things you can do (if you want to become a strong player) is to try to solve any position you see. Practice on positions that occur in somebody else's game or that you see in a chess book or magazine, with or without a label saying “White to move and win!”
Since Black will lose the knight in any case, he at least doubles up the White pawns which are hiding their king. Thus tactics can be used to do more than win pieces or checkmate. They can also be used to bring about a better position in any number of ways.
25. fxg3 Kxg7 26. Kf2.
The fireworks are over.