I don't understand the Caro-Kann defence.

I understand all the major replies to 1.e4, except for the Caro-Kann.

1...e5 opens diagonals for the Bishop and Queen, while placing a pawn in the centre.

1...c5 offers to trade a c-pawn for a central pawn, in effect trading development for control over the centre.

1...e6 sets up an attack on White's e-pawn, allowing for immediate counterplay.

What exactly does 1...c6 do, "philosophically"? After the main line, 2. d4 d5 3. Nc3 dxe4 4. Nxe4, what has Black accomplished? Sure, he put pressure on White's e-pawn -- only to relieve that pressure immediately. It seems that Black has wasted a tempo playing c6, without anything to show for it.

Good question.

Black often succeeds in developing all of his pieces without creating weaknesses or other positional considerations.

The idea is to secure the advantages of the French (solidity) while avoiding the disadvantages (cramped position, the blocked QB).

The defense is solid and sound.  Black's goal is to contest the center and to develop without creating major weaknesses.

It often leads to good endgames for Black, who has the better pawn structure.

http://pathtochessmastery.blogspot.com/2012/05/why-i-play-caro-kann.html

http://www.ericschiller.com/pdf/Caro-Kann%20Basics.pdf

I was, er, instructed to stop misplaying the French and play the Caro-Kann as a low level club player. I have to report that the advice was followed and led to better results: not having that trapped Queen bishop makes life much easier.

It helps to know that a White knight on e5 is often hard to shift and that a major aim of the opening is to play c5 to equalise and avoid being cramped for the whole game.

Just my 2c. I'm no expert at anything related to chess.

I don't have anything to add that hasn't been said above, but rather a somewhat related question:

It's common for black to develop the white-squared bishop early in the Caro-Kann (at least in the Nc3 mainline and advance variation)- whereas in the Slav defence against 1. d4 (which has a similar pawn structure), usually the white-squared bishop isn't brought out so early as not to weaken the queen side. Why is this? Is it because in the Queen's gambit, white's c-pawn is advanced, allowing a quick queenside attack with the white Queen? Can the c-pawn not be advanced early for white vs the Caro Kann without weakening their position?

(Please correct me if any of my above assumptions are incorrect).

In addition to the above great replies, it allows a strong chance for both bishops to be "good" bishops/

Maddolis, in the Slav, if you play Bf5 too early in the Slav, White will have Qb3 to create a timely double attack on b7 and d5 which should lead to an advantage. One notable example is 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 Bf5?!, then 5. Qb3! (Or cxd5 then Qb3) leads to a clear White advantage, for example, 5. Qb3 Qb6! 6. c5! Qxb3 7. axb3 is a fantastic position for White. Instead play 4. ...dxc4 (then 5. a4 Bf5 is a Slav accepted, or 5. e3 b5 leads to an interesting, probably equal queen's gambit accepted, and 5. e4 b5 is a Slav Gambit) or 4. ...e6 (which is likely the better of the two moves, certainly the more fun!).

I should mention also that in the Panov attack Caro Kann (1. e4 c6 2. d4 d5 3. exd5 cxd5 4. c4 Nf6 5. Nc3), Black cannot mess around developing the Queen's Bishop, since it would allow a double attack on b7 and d5, e.g. 5. ...Bf5? 6. Qb3 wins a pawn and leaves Black's position in ruins.

Thanks for the quick responses!
clunney, I'm fairly sure I recall doing a chess mentor exercise with those exact moves, winning the b7 or d5 pawn. I've been playing the Caro Kann for a while and decided to use the Slav for its similarities- though some basic study (as seen above) is certainly required to play solidly. 

Ah right, thanks. I guess I saw those similarities because when I was playing around ~1400, white would most often play the advance variation of the CK.

Speaking of the French and Caro what about exchange variations?  These at least in theory and observation bring piece play to the forefront, which is why I like them.  Mainlines in the others tend to have closed centers and pawn play takes center stage.