user12364: I was watching the current Carlsen vs Adhiban game and I saw a move that always puzzles me:
5. h3 Bh5

I'd say Carlsen want to unpin the knight, or kick the bishop away. The bishop retreats, while keeping pressure on the same diagonal
6. Be2

This move I don't get. I can imagine that 6.g4 would cause positional trouble on the kingside, so the bishop is moved to e2 in order to break the pin.
But if this is true, then why did Carlsen play 5.h3 in the first place ? 
I don't get what does 5.h3 achieve.
Thanks !


user10233: Off the dome:
To support a future g4/h4/h5 push; Protect against Nf6-g4; forces the bishop to a more vulnerable square (h5; make Black make a decision regarding the bishop - exchange it/leave it on the c8-h3 diagonal/move it to h5.

user11245: I would emphasize and simplify @javatutorial's 1st point: 5 h3 restricts the bishop's mobility.  
It used to have freedom to transfer between the kingside and the queenside, but now it cannot reach the queenside during the opening unless it can reach f5 or e4, which is very unusual.  This reduction in the bishop's scope makes it less powerful than it was before, and therefore worse.
So, the main point is to make the bishop a worse minor piece, which is a strategic goal for White in this opening.

user279: I see at least 3 good points to 5. h3:

first and foremost, it puts a question to the Bishop: if Black wants to maintain the pin, he will have to move it to h5, which is more vulnerable and decentralized. Moreover, once the Bishop will be on h5, white squares on the Queenside will become vulnerable, as the Bishop cannot retreat and defend them in one move (just have a look to b7, for example);
once the Bishop is on h5, White can kick it away with g4 if he wants, gaining space and advancing a Pawn with tempo;
now that h3 is in place, h2 becomes a comfortable flight square for the King if White castles Kingside, thus avoiding first rank weaknesses during the endgame.


12364: <p>I was watching the current Carlsen vs Adhiban game and I saw a move that always puzzles me:</p>

<pre><code>5. h3 Bh5
</code></pre>

<p>I'd say Carlsen want to unpin the knight, or kick the bishop away. The bishop retreats, while keeping pressure on the same diagonal</p>

<pre><code>6. Be2
</code></pre>

<p>This move I don't get. I can imagine that <code>6.g4</code> would cause positional trouble on the kingside, so the bishop is moved to e2 in order to break the pin.</p>

<p>But if this is true, then why did Carlsen play <code>5.h3</code> in the first place ? </p>

<p>I don't get what does <code>5.h3</code> achieve.</p>

<p>Thanks !</p>

<p><a href="https://i.stack.imgur.com/MoOOz.png"><img src="https://i.stack.imgur.com/MoOOz.png" alt="this puzzles me"></a></p>
 10233: <p>Off the dome:</p>

<p>To support a future g4/h4/h5 push; Protect against Nf6-g4; forces the bishop to a more vulnerable square (h5; make Black make a decision regarding the bishop - exchange it/leave it on the c8-h3 diagonal/move it to h5.</p>
 11245: <p>I would emphasize and simplify @javatutorial's 1st point: 5 h3 restricts the bishop's mobility.  </p>

<p>It used to have freedom to transfer between the kingside and the queenside, but now it cannot reach the queenside during the opening unless it can reach f5 or e4, which is very unusual.  This reduction in the bishop's scope makes it less powerful than it was before, and therefore <em>worse</em>.</p>

<p>So, the main point is to make the bishop <em>a worse minor piece</em>, which is a strategic goal for White in this opening.</p>
 279: <p>I see at least 3 good points to <code>5. h3</code>:</p>

<ul>
<li>first and foremost, it puts a question to the Bishop: if Black wants to maintain the pin, he will have to move it to <code>h5</code>, which is more vulnerable and decentralized. Moreover, once the Bishop will be on <code>h5</code>, white squares on the Queenside will become vulnerable, as the Bishop cannot retreat and defend them in one move (just have a look to <code>b7</code>, for example);</li>
<li>once the Bishop is on <code>h5</code>, White can kick it away with <code>g4</code> if he wants, gaining space and advancing a Pawn with tempo;</li>
<li>now that <code>h3</code> is in place, <code>h2</code> becomes a comfortable flight square for the King if White castles Kingside, thus avoiding first rank weaknesses during the endgame.</li>
</ul>
