Or B g5 if its the other knight etc?
I understand that we are putting pressure on blacks knight but if he just goes p h6 we have to either trade (which is pretty bad and most ppl dont) or we have to retreat our bishop. By retreating we let black develop his pawn while we just spend time doing nothing. And we also break the rule of moving a piece twice. If black then goes p g5 we AGAIN are forced to move our bishop for the 3rd time.

All this while black gets free development on his pawns. Why would this strategy of "pressuring" the knight ever be good?

What ive been doing instead is moving bishop to d3 (after p d4). Isent this more solid?

Im a bit new to chess.
Any thoughts are approciated!

It totally depends on the position - you can't make a general rule.

But ok - often times the advance of Black's pawns a6 and b5 or h6 and g5 weakens his position. Just take this example - 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 b5 5.Bb3 compared to the position after 1.e4 e5 2.Nf3 Nc6 3.Bc4 - The Bishop is a bit better on b3 than c4 (it can more easily retreat to c2 if needed and it won't be attacked in the event of an eventual d5 by Black) and Black's advanced pawns don't improve his game very much and may come under attack with a2-a4 by White.

Often when White plays Bg5 it can be very dangerous to break the pin with h6 and g5 because Black's Kingside is too weak.

For example - 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 Be7 (Black can't play h6 right away because White takes on f6 and Black would have to take back with the pawn). 5.e3 h6 6.Bh4 g5 7.Bg3 - this is a very bad position for Black since his King will not be safe anywhere on the board.

Sometimes White can sacrifice a Knight on g5 and create a strong attack - for example 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Nc3 Nf6 5.d3 0-0 (considered to be a mistake) 6.Bg5 h6 7.Bh4 g5 8.Nxg5 hxg5 9.Bxg5 with two pawns for the piece and good attacking chances.

Also there are many positions where it can be advantageous to exchange on c6 or f6 and weaken the opponent's pawn structure. For example 1.e4 c5 2.Nf3 Nc6 3.Bb5 g6 4.Bxc6 is a popular line - many players consider it worth giving up the Bishop to give Black weak pawns.

Alright thank u very much for the help!! Will definetly study this a bit to improve

Vivek - this is a good question and I think lkasigh answered it pretty well. One thing I noticed in your thought process is placing piece development on the same level as pawn development. This is generally not how experienced players think; in fact, the word 'development' usually isn't even used in regards to pawns. Pieces, virtually always, should be developed, as their utility is severely limited on their starting squares. It's not nearly as cut and dry whether pawns should be advanced/developed. Sometimes it's good, but sometimes the pawns would be better off back where they started. If you were to advance all of your pawns early on, for an extreme example, your defense would be gone and you'd almost surely get checkmated.

The point of all this is more to say, if you develop a bishop to b5 or g5, and your opponent 'kicks' it with a pawn move like a6/h6, don't think of it as losing a move, especially if your bishop has another perfectly good square to go to, which it does in your examples. And DEFINITELY don't think of it as moving a piece twice in the opening. That applies to moving a piece twice on your own accord (like if you played Bc4, and then Bb5 unprovoked).

Thx army. Much approciated!

The main idea is to keep the edge, making it impossible for black to come out to equality with d5 or c5. The pressure on bishop indirectly does this and thats why its considered to be the best way for white to play. It might actually have more merit in more openings than is currently considered, it often being a difficult move for black to deal with.

Isn't it more straight forward than all that? Every opening is trying to directly or indirectly control some subset of the central squares (e4, d4, e5 and d5). A knight on c6 helps control d4 and e5. By playing Bb5 you're threatening that protection. So, for example, after 1. e4 e5 (white controls e4 and d5 right off and black controls d4 and e5) 2. Nf3 Nc6 (attacking and supporting e5 and d4) 3. Bb5 (attacking the piece that helps support the squares black has staked out). If you're playing to control the dark central squares as black, this may be a perfectly fine move for white. Otherwise it may not necessarilly be as good.