Chess Opening Theory/1. e4/1...e6/2. d4/2...d5/3. e5

=French Defence - Advance Variation= White gains some space advantage immediately, and prevents Black from developing their king's knight to its most natural square f6.

Because Black's position is somewhat cramped at the moment, they usually decide to undermine White's pawn chain on d4/e5, which hinders Black from developing the pieces of their kingside to good squares. This is typically done by attacking the base of White's pawn chain - d4 - by playing 3...c5.

Theory table
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1.e4 e6 2.d4 d5 3.e5