A Useful Waste of Time
Today I am going to talk about the h2-h3 (h7-h6 for Black) move in an opening.
Let me tell you right away that in the majority of the cases when my students (mostly kids) play this move, it means only one thing: they find themselves in an unfamiliar situation, they don't know what to do, so they play h2-h3 'just in case'. Of course in this case the h2-h3 (or h7-h6) is practically always just a waste of time. Moreover, in some cases such a move can actually hurt your position since the pawn structure of your future king's side castle will be potentially weakened (we will discuss such a situation later). But sometimes the h2-h3 or h7-h6 moves can be useful and today we are going to discuss such cases.
The most popular case of the useful rook pawn move is the prevention of a very unpleasant pin. Sometimes such a pin can be so bad that it actually ruins your whole game! The following game is a very good example.
White is already experiencing some serious problems. There is a nasty threat Nc6-d4 and white's kingside will be completely ruined after Black captures the white Nf3. But for now White can easily prevent this threat by pinning and then eventually eliminating the dangerous Nc6.
So, black's Nc6 is gone and therefore there is no immediate threat, and yet White's position is still quite unpleasant. The pin has really paralyzed White pieces since the Nf3 cannot move due to the obvious loss of the Qd1, but the Qd1 cannot move anywhere besides the e2 square (where the Nf3 will be still pinned) because then Black captures the Nf3 and ruins white's whole kingside. White has suffered for a long time and being desperate to break the pin, he played g2-g4. But such moves usually make your whole kingside very weak and lead to serious consequences.
For example, in the recent article ( http://www.chess.com/article/view/classical-games-everybody-should-know-isolated-pawn ) we analyzed four cases of such a dangerous pin-breaking pawn move. Try to find the way Black punished his opponent for his mistake: