Ideas behind each sicilian? What are the key ideas behind each mainline open Sicilian as black? I am normally an e4 player as white, so I am fairly well acquainted with the types of positions that come out of the Sicilian. I am looking to change my black opening repertoire to include the Sicilian but want to better understand black's ideas for each.

I know that as a (very) rough summary, the main ideas are a Queenside counter attack, looking to find the right opportunity to create a d5 pawn break, and to utilise a minority attack on the Queenside. However, I'm struggling to understand more specific ideas.

What are the main ideas after

1. e4 c5 2. Nf3 d6


Here, I know it often leads into a Najdorf and occasionally a Dragon, but don't fully understand the ideas as Black. I am ignoring 3. Bb5+, as play is fairly straight forward with less tactical ideas.

1. e4 c5 2. Nf3 Nc6


For me, 9 times out of 10 it leads to a Sveshnikov. Again, apart from wanting to create a d5 pawn break, I don't see the main goal as Black.

1. e4 c5 2. Nf3 e6


Unfortunately, there are very few people at my level who play this version of the sicilian (relative to the other more popular ones), so I have very little idea of what do. As white, I generally just go by general principles that are present in 2...d6 and 2...Nc6. However, as Black I have very little idea of the goal in this line. It seems to be similar to a Najdorf, without black having the option of e6, or e5 as their e-pawn move.

LEVEL: I am looking for a scientific/objective answer as to Black's ideas in the sicilian, but if there is a personal/playstyle reason for not learning it, I was about 1800-1900 rated. I stopped playing for a while and am now about 1600-1700. I never really looked at openings in the past, winning most of my games in an endgame battle, but I am bored and looking to try something new and exciting :)

Thanks to any replies.
I suggest you first look at the ideas behind the systems you mentioned (e.g. Dragon, Najdorf, Sveshnikov), because in the Sicilian, black's second moves cannot be judged without looking at the intended setup, i.e. black's 4th, 5th and 6th move. These moves are often interchangeable, since white cannot play any forcing moves (apart from 3.d4, of course).

A few stray remarks:


A very common setup is putting pawns on d6 and e6. 30 years ago, this was called the Scheveningen and played by
1.e4 c5 2.Nf3 d6 (or e6) 3.d4 cxd4 4. Nxd4 Nf6 5.Nc3 e6 (or d6). Nowadays it is played by 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4. Nxd4 Nf6 5.Nc3 a6 and 6....e6 in order to avoid 6.g4, and is called "the Najdorf". This is (in my opinion) unfortunate because the "real" Najdorf is defined by putting your pawn to e5, and this is a much greater difference than if e6 is played on move 5 or 6. The Scheveningen can also be reached via 1.e4 c5 2.Nf3 Nc6 (or d6) 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 d6 (or Nc6) and 6....e6, which is called the "Classical Sicilian". Of course there are Scheveningen variations where you put your knight to d7 instead of c6. You see, if you intend to play a Scheveningen style setup, you can play 2....Nc6, 2....d6, 2....e6 and maybe even 2....a6. The differences are nuances depending on which system white chooses.
If you want to play a Dragon, you can play 2....d6, 2....Nc6 or 2....g6. The move order 1.e4 c5 2.Nf3 Nc6 (or g6) 3.d4 cxd4 4.Nxd4 g6 (or Nc6)is called the "accelerated dragon", and is particularly interesting because you retain the possibility to play d5 in one move, which (for non-obvious reasons) discourages the (very dangerous) systems in which white castles long. The downside is that white can play 5.c4, which leads to a positional game with little attacking chances for black. (4....Nf6 5.Nc3 g6 is problematic because of 6.Nxc6 bxc6 7.e5.)
Variations with 2....e6 and without d6 can have independent value if the bishop is played to c5 or b4. Otherwise it's mostly a move order thing.
Finally, at almost any moment between move 4 and 6 (except if e6 or g6 have been played), it is possible to play e5. Examples are the world famous Najdorf, the Sveshnikov, the Kalashnikov, but also the (older) Boleslavsky variation.


Besides move order aspects in the open sicilian, an important factor for the third move is which Anti-Sicilians you'd rather not play against. For example:


2....d6 3.Bb5+ is different from 2....Nc6 3.Bb5. You can rule out 3.Bb5 on move 3 by playing 2...e6 or 2....g6, and forever by 2...a6.
Whatever you favourite setup against 2.c3 is, if your second move after 2.Nf3 doesn't fit, you might be forced to learn another one, since white can play 3.c3.