Nimzo-Indian Defense

Main line, through 3... Bb4E20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4

...Bb4 pins the knight that supports e4: Black fights for the light squares, often trades on c3 to damage the pawns, and plays structure against the bishop pair. White's knight on c3 is pinned against the king.

Dilworth GambitE20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e4

Kmoch VariationE20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3

Mikenas AttackE20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qd3

Romanishin Variation, after 4. g3E20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. g3

Romanishin Variation, after 4. Nf3E20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. g3 O-O 6. Bg2

White's kingside bishop takes the long diagonal.

Romanishin Variation, English HybridE20

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. g3 cxd4 6. Nxd4 O-O 7. Bg2 d5 8. cxd5 Nxd5

The c-file is fully open.

Three Knights VariationE21

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3

Three Knights Variation, Korchnoi VariationE21

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. d5

Three Knights Variation, Euwe VariationE21

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Nf3 c5 5. d5 Ne4

Three Knights Variation, Shocron GambitE21

1. d4 Nf6 2. c4 e6 3. Nf3 Bb4+ 4. Nc3 c5 5. d5 b5

Spielmann VariationE22

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3

Spielmann Variation, Romanovsky GambitE23

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6

An early pawn trade leaves the c-file as Black's avenue and the d-file as White's - both sides get real winning chances down their own file. White is up material out of the opening - Black is banking on activity to show for it.

Spielmann Variation, Carlsbad VariationE23

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxd2

White has doubled pawns on the c-file.

Spielmann Variation, Stahlberg Variation, through 7... Nxc5E23

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxc5

Spielmann Variation, Stahlberg Variation, after 8. Qc2E23

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qb3 c5 5. dxc5 Nc6 6. Nf3 Ne4 7. Bd2 Nxc5 8. Qc2 f5 9. g3

Sämisch Variation, after 4. a3, through 4. a3E24

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3

Sämisch Variation, Botvinnik VariationE24

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. e3 O-O 8. cxd5 Nxd5

An early pawn trade leaves the b-file as White's avenue and the d-file as Black's - both sides get real winning chances down their own file.

Sämisch Variation, after 4. f3, through 7. cxd5E25

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5

White has doubled pawns on the d-file.

Sämisch Variation, Keres VariationE25

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5 Nxd5 8. dxc5

An early pawn trade leaves the b-file as White's avenue and the c-file as Black's - both sides get real winning chances down their own file.

Sämisch Variation, Romanovsky VariationE25

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5 Nxd5 8. dxc5 f5

Sämisch Variation, after 4. a3, through 6. e3E26

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3 c5 6. e3

The structure hands White the half-open b-file - rook pressure down it is a standing plan.

Sämisch Variation, O'Kelly VariationE26

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3 c5 6. e3 b6

Sämisch Variation, after 4. a3, through 5... O-OE27

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. a3 Bxc3+ 5. bxc3 O-O

Sämisch Variation, after 4. e3, through 6. bxc3E28

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 O-O 5. a3 Bxc3+ 6. bxc3

Sämisch Variation, after 4. e3, through 7... O-OE29

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Bd3 Nc6 6. a3 Bxc3+ 7. bxc3 O-O

Sämisch Variation, Capablanca VariationE29

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Bd3 Nc6 6. a3 Bxc3+ 7. bxc3 O-O 8. Ne2 b6 9. e4 Ne8

Leningrad VariationE30

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Bg5

Leningrad Variation, Averbakh GambitE30

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Bg5 h6 5. Bh4 c5 6. d5 b5

Leningrad Variation, Benoni DefenseE31

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Bg5 h6 5. Bh4 c5 6. d5 d6

Classical VariationE32

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2

Classical Variation, Keres DefenseE32

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 O-O 5. a3 Bxc3+ 6. Qxc3 b6

White comes out of the line with the bishop pair.

Classical Variation, Vitolins-Adorjan GambitE32

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 O-O 5. a3 Bxc3+ 6. Qxc3 b5

Classical Variation, Zurich VariationE33

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 Nc6

Classical Variation, Milner-Barry VariationE33

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 Nc6 5. Nf3 d6

Classical Variation, Noa Variation, through 4... d5E34

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5

Classical Variation, Belyavsky GambitE34

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. cxd5 Qxd5 6. Nf3 Qf5 7. Qd1 e5

An early pawn trade leaves the c-file as White's avenue and the d-file as Black's - both sides get real winning chances down their own file.

Classical Variation, Noa Variation, after 5. cxd5, through 5... exd5E35

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. cxd5 exd5

An early pawn trade leaves the c-file as White's avenue and the e-file as Black's - both sides get real winning chances down their own file.

Classical Variation, Noa Variation, after 5. a3, through 5. a3E36

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3

Classical Variation, Noa Variation, Botvinnik VariationE36

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Nc6

Classical Variation, Noa Variation, Main LineE36

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Ne4

Classical Variation, Romanishin GambitE36

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 c5

Classical Variation, Noa Variation, after 5. a3, through 7. Qc2E37

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Ne4 7. Qc2

Classical Variation, Modern VariationE37

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Ne4 7. Qc2 c5

Classical Variation, Noa Variation, San Remo VariationE37

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Ne4 7. Qc2 Nc6 8. e3 e5

The pawns on d4 and e5 stand in direct tension - the first player to resolve it chooses the structure.

Classical Variation, Berlin Variation, after 4... c5E38

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 c5

Classical Variation, Berlin Variation, Steiner VariationE38

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 c5 5. dxc5 Bxc3+

Classical Variation, Berlin Variation, after 4... O-OE38

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 O-O 5. e3 d5 6. Nf3 c5

Classical Variation, Berlin Variation, Pirc VariationE39

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 c5 5. dxc5 O-O

Classical Variation, Berlin Variation, Macieja SystemE39

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 c5 5. dxc5 O-O 6. a3 Bxc5 7. Nf3 b6

Rubinstein System, through 4. e3E40

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3

Rubinstein System, Taimanov VariationE40

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 Nc6

Rubinstein System, after 4... c5E41

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5

Rubinstein System, Hübner Variation, through 7... d6E41

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Bd3 Nc6 6. Nf3 Bxc3+ 7. bxc3 d6

Rubinstein System, Hübner Variation, after 8. O-OE41

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Bd3 Nc6 6. Nf3 Bxc3+ 7. bxc3 d6 8. O-O O-O

Rubinstein System, Rubinstein VariationE42

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Ne2

Rubinstein System, Rubinstein Variation, Main LineE42

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Ne2 cxd4 6. exd4 O-O 7. a3

An early pawn trade leaves the c-file as Black's avenue and the e-file as White's - both sides get real winning chances down their own file.

Rubinstein System, Rubinstein Variation, Sherbakov AttackE42

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 c5 5. Ne2 cxd4 6. exd4 O-O 7. c5

St. Petersburg Variation, after 4. e3, through 4... b6E43

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 b6

St. Petersburg Variation, after 4. e3, through 6. Nf3E43

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 b6 5. Bd3 Bb7 6. Nf3

Black's queenside bishop takes the long diagonal.