why do you bring your knight to the second rank before your bishop comes out?

i dont get why people want to block their bisops with their knights, I NEED HELP!!!!!!!!!!!!!!

i think it is so you can your knight to g6 or b6 or g3 or b3, or possibly so you can fienchetto your bishop!

thanks, BUT DOES ANYONE ELSE HAVE A DIFFERENT REASON?!!!!!!!!!!!!

If you want some help how about posting a diagram with a position germane to your question, so we can see if you're talking about a "book" line or just some random blunder. Posting the opening moves leading to the position (preferably with a diagram) would be helpful as well.

Another reason is the intention to play f3 or f4 and c3 or c4 without risking to delay your Knights' development too much.

Beside this and the already said reasons, it might be part of your "book moves", meaning that youre playing a well known series of moves which lead to a playable position and were adopted by many very strong players for a number of years (e.g. the Tarrash variation of the French, or Spassky's Ne2 in the Closed Sicilian).

Knights before Bishops! There are a billion reasons why!

1.)Knights contribute more to the Center than a Bishop

2.)You dont want to commit your bishop to a Diagonal until you Know what kind of opening your Opponent is playing. 

3.) Knights protec your pawns and Attack your Opponent's Pawns.

4.) Sometimes you want to keep your bishop so you can pin your oppponents Knight or just to make pressure between pieces. Such as Ruy Lopez.

5.) Knights Prevent the Queen From Coming out through that long Diagonal and attacking your King(Which is very annoying..)(ex. King's Gambit)

Do you need anymore? Knights Before Bishops Unless your playing a SPECIFIC opening such as Ruy Lopez, Guicco Piano, etc...

I used to bring the bishop on second rank more often than the knight. I prefer Knights to be on third rank. :D

The way I understood the question, SukaSkillz was asking why playing Knight to King/Queen 2 instead of Knight to Bishop 3.

Knights was more ideally to be brought outside early as it influenced most of the key squares on the center and can't easily be kicked out by pawns on third rank. 

While bishops -even though they also was a good piece on the center but it easily can be kicked and trapped by pawns.

Where the Knight is developed depends on the opening situation.  You can't just say "I'm going to develop my knight to the third rank" before the game even starts (other than maybe if you are White and intend to play 1.Nf3).

There are pros and cons to each scenario.  Take the French.

1.e4 e6 2.d4 d5.  Black attacks White's e-pawn.  White has 4 options, the last of which I highly would recommend AVOIDING.  Those 4 options are:

1. Exchange the Pawn
2. Advance the Pawn
3. Protect the Pawn
4. Abandon the Pawn

Let's take the 3rd scenario in this case since the top two lines played by masters both involve protecting the pawn.  White has 2 places to put his Queen's Knight to protect e4, d2 or c3.  There are pros and cons to both.

3.Nd2 - Known as the Tarrasch Variation, has the downside that it impedes White's Development.  The Bishop is blocked in temporarily, and in turn, so is the Rook on a1.  However, the d2-knight can't be harassed.  If Black tries to pin it with 3...Bb4, which is a horrible move, White can just play 4.c3, attacking the Bishop, holding on to the Knight, and solidifying his post on d4.  This line is considered to be slow, and often a strategic battle occurs.

3.Nc3 - This can lead to the Winawer Variation (3...Bb4), Classical (3...Nf6 4.Bg5 Be7), MacCutcheon (3...Nf6 4.Bg5 Be7), Burn (3...Nf6 4.Bg5 dxe4) or Steinitz (3...Nf6 4.e5).  White's pieces are not blocked, but there are two downsides to this.  The first is the Knight can be pinned, like in the Winawer or MacCutcheon, which attacks e4 again, and so once again, White must do something about that rather than develop one of his pieces naturally.  The second is that the Knight on c3 impedes a pawn from getting to c3, and so it encourages Black even more to attack d4, and so instead of being able to maintain a pawn on d4, which often is what holds White's position, especially if he also has a pawn on e5.  Black will attack with ...c5 and ...f6, destroy White's pawn center, and if he gets in ...e5 safely, eliminating the backwards e-pawn, opening up the Bad Bishop, etc, Black is likely going to win.

Chess is a balancing act, and everything must be approached on an individual basis, and to say that you are going to develop a certain piece to a certain square no matter what is nuts.  Back when I played the French, if I had to face say, a 1200 player, and he played something off the wall stupid like 1.e4 e6 2.Bc4 (which I have faced more times than you want to imagine), I had to seriously hold my laugh as I seriously wanted to laugh in their face every time!

move 8 for black is what i am talking about

Because the bishop belongs on the a8-h1 diagonal. Black will play b5 which allows the bishop to come to b7 and queenside counterplay with b4 threats. Also, if the knight comes to c6 it slows some of your counterplay on the c file.

White might be planning O-O-O and e5 so you block the queen from rooks.  

Good to know