user28159: In the Alapin variation of the Sicilian, the game goes 1. e4 c5 2. c3. However, this sequence just blocks the b1 knight from its best square, and it doesn't develop anything. Both squares attacked by the pawn are already being attacked by black's other pawn.
What is the point of the move 2. c3? I do understand that it can be used to avoid a mainline Sicilian, but at least develop some other good piece.

user17448: Actually g1 knights best square is f3 and is not blocked - but the point is pretty obvious to take on d4 with pawn and have firm control over central squares. And b1 knight that lost ability to go to c3 either will go to c3 after cxd4 recapture or will be routed into play via a3 or d2.

user14130: I think there was good points and explanation so far, I will just add few.
I recently also started to play Alapin, and there are two points two that:
1- make your opponent uncomfortable! as mentioned before the structure and form of the play is not what black players are looking for, and it make it uncomfortable to face it.
2- Also, white is trying to avoid open sicilian which gives black two central pawn and very unbalanced and dynamic game, here you will generally end up in an IQP position, and play is more dynamic from white and requires static play and patience from black,
so, you change the nature, you make black uncomfortable with minimum risk, it could be a viable option.

user19861: The idea is that c3 supports d4 and if black plays cxd4 then white recaptures with the c-pawn leaving white with the better center. If white is able to carry out that plan then he will have a clear opening advantage. However, in actual play,  the idea is a little slow. After 2...d5 white really doesn't have a good answer. 3. e5 just gives black an improved version of the French while 3. exd5 will likely lead to an IQP position. Plus, it allows black to bring the queen to the center of the board without allowing the typical Nc3 with a gain of time. I'll point out that 2...Nf6 is very good for black for similar reasons.
White's idea of 2.c3 is fundamentally sound. All mainstream openings deal with the central pawn structure in the first 2-3 moves in one way or another. It's just that the actual position on the board makes it impossible for white to get the structure he's trying to get if black plays correctly. Even so, after 2...d5 white is still a little better. The d-pawn will likely become isolated but white still has more space in the center and the open lines will give white a lot of piece activity. If you doubt me, try playing the black side against a strong engine.
Keep in mind, Larsen said the open Sicilian (with Nf3 and d4) was a positional mistake. I'm not sure I completely agree but he does have a point that white is losing something in trading the central d-pawn for black's less valuable c-pawn. The Alapin attempts to solve that by replacing white's d-pawn after it's captured. It doesn't completely succeed but white is able to convert the first move advantage into something (central space and an active position) which gives at least a small positional advantage.

user13012: You are asking a good question, because the answer gets to the root of good opening play. The object of the opening is not just to get the pieces out. If it were, then after 1.e4 c5, 2.Bc4 would be a popular move. The reason why it is not is that c4 is not yet clearly a good square because 2..e6 neutralizes the Bishop, and an eventual ..d5 will take advantage of it. The real object is to get the pieces onto effective squares, and which squares are effective depends on the Pawns.
The Pawns have three tasks. One is to move out of the way and give freedom to the pieces. Another is to create safe and stable locations for the pieces after they are developed. A third is to deny effective squares to the opponent. If it were simple to achieve all three objectives then the opening phase would be easy, but it is part of ones playing style to make personal choices about the importance of each objective. This adds to the fascination of the game.
I am not trying here to explain to you everything that might be said about 2.c3, but rather to help you understand the subtlety that any explanation would need to address.

user26984: The move c3 prepares d4; if Black proceeds blindly by playing, for example, 2. ...Nc6, 3. d4 gives White full control of the centre and a strong advantage.
To prevent White dominating the centre, Black tends to counterattack with 2. ...d5 or ...Nf6, which often leads to French-like structures that can throw off a player with the black pieces who is familiar with Sicilian main lines but not with others.

28159: <p>In the Alapin variation of the Sicilian, the game goes 1. e4 c5 2. c3. However, this sequence just blocks the b1 knight from its best square, and it doesn't develop anything. Both squares attacked by the pawn are already being attacked by black's other pawn.</p>
<p>What is the point of the move 2. c3? I do understand that it can be used to avoid a mainline Sicilian, but at least develop some other good piece.</p>
 17448: <p>Actually g1 knights best square is f3 and is not blocked - but the point is pretty obvious to take on d4 with pawn and have firm control over central squares. And b1 knight that lost ability to go to c3 either will go to c3 after cxd4 recapture or will be routed into play via a3 or d2.</p>
 14130: <p>I think there was good points and explanation so far, I will just add few.</p>
<p>I recently also started to play Alapin, and there are two points two that:</p>
<p>1- make your opponent uncomfortable! as mentioned before the structure and form of the play is not what black players are looking for, and it make it uncomfortable to face it.</p>
<p>2- Also, white is trying to avoid open sicilian which gives black two central pawn and very unbalanced and dynamic game, here you will generally end up in an IQP position, and play is more dynamic from white and requires static play and patience from black,</p>
<p>so, you change the nature, you make black uncomfortable with minimum risk, it could be a viable option.</p>
 19861: <p>The idea is that c3 supports d4 and if black plays cxd4 then white recaptures with the c-pawn leaving white with the better center. If white is able to carry out that plan then he will have a clear opening advantage. However, in actual play,  the idea is a little slow. After 2...d5 white really doesn't have a good answer. 3. e5 just gives black an improved version of the French while 3. exd5 will likely lead to an IQP position. Plus, it allows black to bring the queen to the center of the board without allowing the typical Nc3 with a gain of time. I'll point out that 2...Nf6 is very good for black for similar reasons.</p>
<p>White's idea of 2.c3 is fundamentally sound. All mainstream openings deal with the central pawn structure in the first 2-3 moves in one way or another. It's just that the actual position on the board makes it impossible for white to get the structure he's trying to get if black plays correctly. Even so, after 2...d5 white is still a little better. The d-pawn will likely become isolated but white still has more space in the center and the open lines will give white a lot of piece activity. If you doubt me, try playing the black side against a strong engine.</p>
<p>Keep in mind, Larsen said the open Sicilian (with Nf3 and d4) was a positional mistake. I'm not sure I completely agree but he does have a point that white is losing something in trading the central d-pawn for black's less valuable c-pawn. The Alapin attempts to solve that by replacing white's d-pawn after it's captured. It doesn't completely succeed but white is able to convert the first move advantage into something (central space and an active position) which gives at least a small positional advantage.</p>
 13012: <p>You are asking a good question, because the answer gets to the root of good opening play. The object of the opening is not just to get the pieces out. If it were, then after 1.e4 c5, 2.Bc4 would be a popular move. The reason why it is not is that c4 is not yet clearly a good square because 2..e6 neutralizes the Bishop, and an eventual ..d5 will take advantage of it. The real object is to get the pieces onto effective squares, and which squares are effective depends on the Pawns.</p>
<p>The Pawns have three tasks. One is to move out of the way and give freedom to the pieces. Another is to create safe and stable locations for the pieces after they are developed. A third is to deny effective squares to the opponent. If it were simple to achieve all three objectives then the opening phase would be easy, but it is part of ones playing style to make personal choices about the importance of each objective. This adds to the fascination of the game.</p>
<p>I am not trying here to explain to you everything that might be said about 2.c3, but rather to help you understand the subtlety that any explanation would need to address.</p>
 26984: <p>The move c3 prepares d4; if Black proceeds blindly by playing, for example, 2. ...Nc6, 3. d4 gives White full control of the centre and a strong advantage.</p>
<p>To prevent White dominating the centre, Black tends to counterattack with 2. ...d5 or ...Nf6, which often leads to French-like structures that can throw off a player with the black pieces who is familiar with Sicilian main lines but not with others.</p>
