Sicilian Defence Online Chess Opening

The Sicilian Defence is a chess opening that begins with the moves 1.e4 c5.

At the master level, the Sicilian is the most popular and best-scoring response to White's first move 1.e4. One sixth (17%) of all games between grandmasters, and one quarter (25%) of the games in the Chess Informant database, begin with this opening. Grandmaster John Nunn notes that the reason for the Sicilian Defence’s popularity “is its combative nature; in many lines Black is playing not just for equality, but for the advantage. The drawback is that White often obtains an early initiative, so Black has to take care not to fall victim to a quick attack.” The earliest recorded notes on the Sicilian Defence date back to the late 16th century by the Italian chess players Giulio Polerio and Gioachino Greco.

By advancing the c-pawn two squares, Black asserts control over the d4-square and begins the fight for the centre of the board. This move thus fulfills the same purpose as the move 1…e5, the next most common response to 1.e4. Unlike 1...e5, 1...c5 also breaks the symmetry of the position, which strongly influences the future actions of both players. Having pushed a kingside pawn, White tends to hold the initiative on that side of the board. Meanwhile, Black has advanced a pawn on the opposite wing, giving him an advantage in space on the queenside, and provides a basis for future operations on that flank. Often, Black's pawn on c5 is traded for White's pawn on d4 in the early stages of the game. This opens the c-file for Black, who can place a rook or queen on that file to aid his queenside counterplay.

History
The Sicilian Defence was named by Giulio Polerio in his 1594 manuscript on chess. It was fairly popular in the nineteenth century; Louis-Charles Mahé de La Bourdonnais, Howard Staunton and Louis Paulsen all played it with some consistency. It went through a period of relative neglect in the early twentieth century. Capablanca, the third world chess champion from 1921 to 1927, famously denounced it as an opening where “Black’s game is full of holes.” Its fortunes were revived in the 1940s and 1950s by players such as Isaac Boleslavsky, Alexander Kotov and Miguel Najdorf. Afterwards, Bent Larsen, Ljubomir Ljubojevic, Lev Polugaevsky, Leonid Stein, Mark Taimanov, and Mikhail Tal all made extensive contributions to the theory of the defence.

Through the efforts of world champions Bobby Fischer and Garry Kasparov, the Sicilian Defence became recognized as the defence that offered Black the most winning chances against 1.e4. Both players favoured sharp, aggressive play and employed the Sicilian almost exclusively throughout their careers, giving the defence its present reputation. Today, most leading grandmasters include the Sicilian in their opening repertoire. Some of the current top-level players who regularly use it include Viswanathan Anand, Boris Gelfand, Vassily Ivanchuk, Alexei Shirov, Peter Svidler and Veselin Topalov.

Source