Is this the Bobby Fischer move (Bb3) and why is it so important?

I admit f4 is not good in this position (10. f4), but can someone explain why Bb3 is so necessary or advisable in positions like this?

Welcome back.

How is it safe when Na5 could be played and capture the bishop?

Here is a game where the other knight picked off the bishop.

Can you be more specific? In the game I played, it appears the problem move I made was 7. N5a3 instead of 7. N5c3, not 10. Bb3.

In the 1st game the threat is 10...b5 11 Bb3 b4 forking a knight.
In the 2nd game the threat is 7...Nxe4 8 Nxe4 d5 solving all problems for black.
Fischer himself commented Bb3 is a waiting move that cuts down blacks options.

"In the 1st game the threat is 10...b5 11 Bb3 b4 forking a knight."

Yea, you are stating the obvious Charlie. So, what should white do then or should have done instead?

"Fischer himself commented Bb3 is a waiting move that cuts down blacks options."

Is it concluded these early waiting moves are good or is it deemed a waste of tempo?

Would an earlier Bb5 or Bb5+ have been better? Or another option?

#10

"So, what should white do then or should have done instead?" Bb3 to pre-empt b5-b4.

"Is it concluded these early waiting moves are good or is it deemed a waste of tempo?" Fischer said this is good and a tempo well used. If Bc4 has to retreat to b3 after b5, then it is forced. If it retreats before white has more liberty.

"Would an earlier Bb5 or Bb5+ have been better?" Oh no, the bishop is worth more than the knight. Fischer won many games just based on the power of his Bb3. There are variations with Bb5 (Rossolimo 1 e4 c5 2 Nf3 Nc6 3 Bb5) and Bb5+ (Moscow 1 e4 c5 2 Nf3 d6 3 Bb5+) but those are entirely different from variations with Bc4.

It did, but

(a) That knight traveled from the other side of the board.

(b) That bishop wasn't terribly active anyway.

(c) The top engine move is actually to move the bishop. 14. Bd5. If black replies exd5, then white attacks with the knight 15. Nxd5 Nxd4 16. Bxd4 17. Qd8 Nf6+ 18. Bxf6 gxf6 and then white's heavy king side attack continues. But 14. Qh5 followed by 15. Ne1 allowed black to narrowly win the race by attacking queen side.

So yeah, the bishop can fall on b3, but it can anywhere else too.

In terms of a defensive reason, I'm guessing that it's simply to use up a tempo so that black doesn't have the typical tempo gains which would speed up an attack once in motion. For example, on c4, the bishop is vulnerable to b5, gaining a tempo, which means b4 can be executed quicker. Major pieces also come to the c-file which is another instance in which it's beneficial to not allow it to come with tempo.

I like to drop the Bishop back to b3 in the Italian. It is something to do and it is handy later.

Na3 is a bad knight position and if possible you will want to reroute it through Nc4.

it's to avoid any pawn moves that could target the bishop, like b5 and d5.