Chess Opening Theory/1. d4/1...Nf6/2. c4

White takes more space and increases the control of the important d5 square. This move order allows White's queenside knight to develop to the active c3 square without blocking the c-pawn.

Black has a range of different responses and two main plans: contest White's centre immediately with pawns in the classical way, or focus on development and open lines for their bishops, in the hypermodern way.

Capablanca warns us that "two or more pawns are strongest when they are in the same rank next to one another."^[1] Therefore Black may wish to to assault White's pawn centre to force some weaknesses.

2...c5 is the Benoni defence. Typically White keeps the d-pawn in the centre with 3. d5, and Black tries to attack the pawn chain and play on the queenside. The main continuations are 3...e6, the Modern Benoni (often aggressive, risky), or 3...b5, the Benko gambit (positional pawn sacrifice by Black on the queenside).

2...e5 is the Budapest defence. It has a unique character and often allows Black active play. It offers the e5 pawn with tempo on the knight, 3. dxe5 Ng4, but White usually gives the pawn back eventually. White usually gets a slightly better position, but Black can do well against an unprepared opponent.

Black can't transpose into a Queen's gambit declined right now. 2...d5 is the Marshall defence. This allows 3. cxd5 Nxd5 4. e4 Nf6⩲, and White gets a big centre and the advantage.

In order to develop their pieces, Black will have to first choose a pawn move to free one of their bishops. Typically the approaches are to free the bishops with ...d6 and ...g6 (what Tartakower called "Old Indian defences") or ...e6 and ...b6 (what Tartakower called the "Neo-Indian defences").

2...e6 is the most common move. It is solid and flexible, and prepares to develop the kingside bishop along the a3-f8 diagonal. It also gives Black the option to transpose into a Queen's gambit declined with ...d5. Depending on how White plays and Black responds, this can lead a Queen's Indian defence with ...b6, Nimzo-Indian, Bogo-Indian, Benoni, or a Catalan games.

2...b6 is the Accelerated Queen's Indian. Black prepares to fianchetto their queenside bishop. It is "accelerated" as the Queen's Indian is usually reached through the move order 2...e6 3. Nf3 b6.

2...g6, sometimes called the West Indian, prepares to fianchetto the kingside bishop. This tends to be a more combative approach. This typically leads to a King's Indian defence, or a Grünfeld after 3. Nc3 d5.

2...d6 is called the Old Indian. This opens the c8-h3 diagonal for the bishop, but Black often develops his knight to d7 first. This can transpose into the King's Indian defence (e.g. 3. Nc3 g6 4. e4 Bg7), but there are lines with their own flavour where Black plays ...e5, ...Be7, and ...O-O.

• 2...c6 is the rare Slav Indian, looking for a transposition to the Slav Defence. White typically allows this with 3. Nc3 or 3. Nf3, but can refuse with 3. Bf4.
• 2...Nc6 is the Mexican defence or Black knights tango. Though the knight can be kicked immediately wit 3. d5, it safely relocates to 3...Ne5. The mainline goes 3. Nf3 (preventing ...e5) e6 4. Nc3 Bb4.

For explanation of theory tables, see theory table and for notation, see algebraic notation..

1. d4 Nf6 2. c4

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Wikipedia has related information at Indian Defence

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.