It is not always clear to me why a best move is a best move

Example nl.lichess.org/training/opening/1055
This puzzle tells me Bg4 is the best move to make.
I would think the bisshop will only be chased around by the pawns.
How do you proceed in working something like this out. It would be nice if I could figure out for myself that this is indeed the best move or maybe that I dont agree.

I could be wrong, but my guess is that opening trainer here is based on concrete opening theory, here's a link to the position you mentioned:
http://www.365chess.com/opening.php?m=14&n=17377
It could occur in the sicilian defense (delayed alapin) for example, and the database says that the next move is 7. ... Bg4 88.6% of the time here.

Also, you can click the "Analyze" button, then turn on the local engine evaluation, then you can proceed with the moves you think are gonna happen and see the engine's response to them.

Yes, i found something similar in chessopenings.com, but it gives statistics. So apparently in general chess players think this is a good move. But this gives no explanation why this is a good or the best move.

Also in this puzzle, beneath it, it says:
"Sicilian Defense, Nyezhmetdinov-Rossolimo Attack
Sicilian Defense, Canal Attack
Zukertort Opening, Sicilian Invitation"
How can I use this, where to go, where to begin?

I dont know a single opening, I want to start explore this.

Hey,

I think you guys are trying to approach chess and openings the wrong way.

Just learn the principles of openings (doing something to control the center, develeoping your pieces and castling before attacking). And then apply those guidelines.

In that position (lichess.org/training/opening/1055) there are many good moves. For example I would have played g6 to prepare Bg7, here computer said "good move, but there is a better one".

Computers do not understand chess. I would recommend not trying to be like the computer, because there are no absolute truths in chess. Computers offer an illusion that there is an absolute truth.

Chess is not about knowing 100% sure absolute continuations. It'sabout knowing that every rule can be broken. It's about freeing your mind. It's about being in the moment, being in the flow state of mind. Like a boxer in midfight.

So yeah, listen to the rules and principles, but do not let them ensalve you. If you think Bg4 is right because computer said so you are making chess into a memorizing game where some calculator is your god.

Just play the game and have fon FOR F*** SAKE!

peace :)

Totally agree with you, @NoLuckOnlySkill.

I always here that opening are not to be studied by beginners, rather opening principles (like you mentioned) and a ton load of tactics, and maybe some end-game study, then comes strategy and opening lines.

To answer your question @Stuiter, there are many ways to do that, one I like is memchess.com, but as @NoLuckOnlySkill mentioned, this should not be your priority for now.

He can't chase you off, he would ruin his king pawns.

The idea of ..Bg4 is to follow up with ..e6 and ..d5 when black has a french structure, but without the bad bishop c8 blocked by his own e6 pawn.

To add to what Tim said, it's also to avoid giving white a big center. In this position black can't really force white to overextend his center(as in the benoni- though white retains an adv ofc) and black can't hit with e5 due to likely weaknesses so he either plays g6 and deals with white's advantage or allows the possibility of giving up the bishop pair and not only restricts white's center but has a very clear plan. Also bd7 is generally bad when white has ideas of pushing the e pawn- see modern baloney theory