Why do strong players play the Sicilian?

Because it unbalances the game from move one. After the exchange on d4 Black has two centre pawns to White's one and a half-open c-file, while White has a lead in development and space on the kingside. Neither side can shuffle towards a draw, so a player who wants to win with Black has a real position to work with rather than a symmetrical one.

Is the Sicilian hard to learn?

It is the hardest of the main defences, and the reason is asymmetry. White chooses between the Open Sicilian, the Alapin with 2.c3, the Grand Prix with 2.Nc3 and f4, the Smith-Morra gambit and half a dozen more, and each needs a different reply. Playing 1...e5 you meet three or four serious tries; playing 1...c5 you meet ten.

What is the Open Sicilian?

The main line: 1.e4 c5 2.Nf3 followed by 3.d4 cxd4 4.Nxd4, where White gives up the d-pawn for the c-pawn and gets a big lead in development. Almost all the famous Sicilian variations, the Najdorf, the Dragon, the Sveshnikov and the rest, are ways of meeting the Open Sicilian, and they run twenty moves deep in theory.

The Sicilian Defence for beginners

1.e4 c5. Black declines to copy White and starts a different game: a wing pawn goes for a centre pawn, the c-file opens for a black rook, and the two sides end up attacking on opposite halves of the board.

The Open Sicilian: 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3, the starting point of the Najdorf, the Dragon and most of the rest.

After 5.Nc3. Black's c-pawn is gone and White's d-pawn with it: Black has pawns on d6 and e7 against White's lone e4, and the c-file is open for a rook on c8.

What the trade on d4 buys

Count the pawns after 4.Nxd4. White has one centre pawn, on e4. Black still has the d-pawn and the e-pawn, so in a pure endgame Black is the one with the better structure. That is the long-term half of the deal.

The short-term half belongs to White, who has a knight on d4, a knight coming to c3, and a free hand to castle either side. Castle queenside, throw the g- and h-pawns forward and the game becomes a race: White mates on the kingside or Black gets there first down the c-file. Sicilian games are not quiet.

Why I do not give it to beginners

Not because it is unsound. Because of the sheer number of things your opponent can do.

Meet 1.e4 with 1…e5 and you need answers to the Italian, the Ruy Lopez, the Scotch and a couple of gambits. Meet it with 1…c5 and you need answers to the Open Sicilian, 2.c3, 2.Nc3, 2.d4 as a gambit, 2.Bc4 and the rest, and in the Open Sicilian the theory keeps going past move fifteen. Lose the thread on move eight and your king is in the middle with an open e-file pointed at it.

There is also a habit problem. Sicilian positions are won by counterattack, and counterattacking is a skill you develop after you can defend, not before. Start with 1…e5 and come back.

A setup if you want it anyway

Play the version with the fewest forcing lines: 1.e4 c5 2.Nf3 e6, then …a6, …Qc7, …Nf6, …Bd6 or …Be7, and castle. No early …g6, no early …d5, no Dragon. You will not win many games in fifteen moves, and you will not lose many either, and that is the right trade while you learn what the pawn structure wants.

Then work on the thing that actually decides Sicilian games: calculation. In an opening where both kings are being attacked at once, the player who counts one move further wins, and no amount of memorised theory substitutes for that.