Answer 1.e4 with 1...c5, trade the c-pawn for White's d-pawn to open the c-file, then develop and play for active counterplay on the queenside while watching the centre. The shown line is the Najdorf, the Sicilian's most respected main line.
Strengths
...c5 fights for the centre from the side: Black aims to trade the c-pawn for White's d-pawn and gain the half-open c-file for the rooks.
Black willingly gives White a space and development lead in exchange for a sound pawn structure and long-term queenside chances.
The half-open c-file is Black's highway — rooks and a queen pressing down it, often with ...Rc8 and pressure on c2 or the c3-knight.
In the Najdorf, the small move ...a6 stops White's pieces using b5 and quietly prepares ...e5 or ...b5 to expand and take the initiative.
Watch out for
Don't drift into passivity: the Sicilian is about counterplay, so a Black setup with no active plan on the queenside just hands White a free attack.
Be careful castling kingside if White has stormed pawns up with f3, g4, h4 — know when to delay castling or castle into the safer side.
Avoid grabbing loose pawns (like the b2-pawn) too early and falling behind in development while White's pieces pour out.
Learn the moves above, play them from memory, then spar the Sicilian Defense as Black against the computer — the moves you miss come back for review until you know them by heart. Want the full ideas, plans and FAQs? See the Sicilian Defense guide.