Chess Opening Theory/1. d4/1...Nf6/2. c4/2...c5/3. d5

White keeps their central pawn and takes more space in the centre. White's pawn dug in on d5 cramps Black's position. How Black will crack the pawn chain, now or later, determines the direction of the game.

3...e6, the Modern Benoni, attacks the tip of the pawn chain. After the trades 4. Nc3 exd4 5. cxd4 d6 6. e4, Black surrenders space to White and has a weak pawn on d6, but in return gets excellent play on central dark squares, a queenside majority, and use of e5. Black's main ideas are to play on the queenside, while White targets the weak d6 and attacks on the kingside.

3...b5, the Benko or Volga gambit, targets the base of the pawn chain. Black's idea is long term positional pressure: they offer a pawn in the hope of opening the b and a files for their rooks and a single kingside pawn island. This is the mainline today.

Black can focus on developing before deciding how to attack White's centre.

3...d6, planning an eventual break on e6, is called the Hromádka system. The pawn on d6 controls e5, prevents e2-e4-e5 kicking Black's knight, and affording Black time to develop with ...g6, ...Bg7, and ...O-O. ...d6 also freed the d7 square for Black's queenside knight, who otherwise was relegated to developing to a6 on the side of the board.

Black can start with their kingside development first instead, 3...g6. Once White plays e4, Black is compelled to play ...d6 to prevent e5! and these approaches transpose.

Black can choose to play around the pawn chain instead.

3...e5?!, the Czech-Benoni, looks to close up the centre instead. After 4. Nc3 d6 5. e4 however, White is afforded much more space and can play for pawn breaks on either flank.

3...Ne4?! the Vulture defence, was a sideline popular in the 90s.

3...e6, the Modern Benoni, was popular in the 1970s-1980s with counter-attacking players like Champions Tal, Fischer, and Kasparov, until the discovery of of the Taimanov variation, 4. Nc3 exd5 5.cxd5 d6 6.e4 g6 7.f4 Bg7 8.Bb5+!, rendered the Benoni all but unplayable.

Thus, nowadays most players will choose a different move-order to reach the Benoni: 1. d4 Nf6 2. c4 e6, and if White plays 3. Nc3, then Black satisfies himself with 3...Bb4, the Nimzo-Indian, but if White plays the anti-Nimzo with 3. Nf3, then after 3...c5 4. d5 exd5 5.cxd5 d6 6. Nc3 g6 then f4 is no longer possible. White will have to satisfy himself with either the old main line, 7. e4 Bg7 8. Be2, the current main line, 7. h3 Bg7 8. e4 O-O 9. Bd3, or the Fianchetto Variation, 7. g3 Bg7 8. Bg2.

The Benko or Volga Gambit was revived by Hungarian-American grandmaster Pal Benko in the early 1970s after it enjoyed a brief period of popularity in the mid-1950s. However, today it is judged as +/= because Black has no tactical chances, and practice has shown that White can weather the storm, keeping his extra pawn. Alternatively, the Zaitsev line is very sharp and complicated, when White plays 5. Nc3 axb5 6. e4 b4 7. Nb5.

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

1. d4 Nf6 2. c4 c5 3. d5

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Wikipedia has related information at Benoni Defence

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