Classical Defense, Normal Line

The Normal Line arises when White answers 5...c5 in the Classical Defense of the Queen's Gambit Accepted by castling with 6. O-O, the most frequent choice in the position. White does not resolve the tension with dxc5 and does not prepare e4 with Qe2. Instead the king is brought to safety and the d4-pawn is left under attack, with White willing to accept an isolated queen's pawn if Black exchanges with ...cxd4 and White recaptures with exd4. The bishop on c4 remains a target for a queenside pawn advance, and that shapes Black's options.

The most popular reply, played in close to half of games, is 6...a6, the Main Line, which prepares ...b5. White can then allow the advance with 7. Qe2, the Alekhine System, or prevent it with 7. a4, the Rubinstein Variation. Each of two other replies accounts for roughly a quarter of games. 6...Nc6, the Steinitz Development Variation, adds pressure on d4. 6...cxd4, the Steinitz Exchange Variation, settles the central structure at once. The engine rates the position as close to equal, and Lichess results are nearly even.