Ruy Lopez, Steinitz Defense

The Ruy Lopez arises after the king pawns advance, White develops the knight to f3, and the bishop moves to b5, where it pressures Black's knight on c6. The Steinitz Defense is identified when Black advances the d7-pawn to d6 on the third move, written 3...d6. The pawn on d6 supports Black's e5-pawn. The basic idea is to make the center secure before completing development. Development means moving knights and bishops from their starting squares to useful positions. The price is reduced space, meaning fewer comfortable squares for maneuvering, so Black's pieces may take longer to become active.

White usually tests the setup by advancing the d2-pawn to d4, written 4.d4, to challenge the center. Black may develop the c8-bishop to d7 so that, if White's bishop captures the c6-knight, Black can recapture with that bishop without changing the pawn structure. Black also commonly moves the g8-knight to f6 and the f8-bishop to e7, then castles, making the single move of king and rook that usually places the king in greater safety. Exchanging the e5-pawn for the pawn on d4 often reduces White's central pressure. Waiting too long can leave Black's pieces crowded behind their own pawns.

This is the Old Steinitz, defined by the immediate 3...d6. In the Modern Steinitz Defense, Black first advances the a-pawn to a6 and makes the bishop retreat before playing ...d6, usually gaining more freedom. The Morphy Defense also begins with ...a6 but can lead to many different systems.