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What is a "Variation"?
A Variation is a specific line of play that branches off from a main opening. Just as a tree has a trunk that splits into branches, a chess opening (like the Sicilian Defense) splits into distinct variations, each with its own name and character.
Example: The Sicilian Defense Tree
The "Trunk" of the tree is the main starting position. For the Sicilian Defense, it begins with the moves 1.e4 c5.
Fig 1: The Root. The position after 1.e4 c5. From here, the game branches out.
...And here come the Branches (Variations)
Depending on how Black and White respond next, the game can transform into completely different battlefields.
(5...a6)
The "Rolls Royce" of openings. Aggressive, complex, and theoretical.
(5...g6)
Black fianchettoes the bishop. A sharp, tactical fight often involving opposite-side castling.
(2.Nc3)
White avoids the open d4 break. A slower, maneuvering game with closed lines.
Why does this matter? You cannot just "Play the Sicilian." You must choose a specific Variation. A Najdorf player faces completely different patterns than a Dragon player.