In chess

Chess

Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...

, the East Indian Defence is an opening

Chess opening

A chess opening is the group of initial moves of a chess game. Recognized sequences of opening moves are referred to as openings as initiated by White or defenses, as created in reply by Black. There are many dozens of different openings, and hundreds of named variants. The Oxford Companion to...

 characterised by the move order

1. d4 Nf6

2. Nf3 g6

It has a close kinship to the more common King's Indian Defence

King's Indian Defence

The King's Indian Defence is a common chess opening. It arises after the moves:Black intends to follow up with 3...Bg7 and 4...d6.The Grünfeld Defence arises when Black plays 3...d5 instead, and is considered a separate opening...

 and is often considered a variant thereof. The difference is that White has not yet played c4, and therefore retains some options.

If White plays an early c4, the opening will transpose

Transposition (chess)

A transposition in chess is a sequence of moves that results in a position which may also be reached by another, more common sequence of moves. Transpositions are particularly common in opening, where a given position may be reached by different sequences of moves...

 into a King's Indian. It is also possible for White to support an early e4 advance, transposing into the Pirc Defence

Pirc Defence

The Pirc Defence |grandmasters]]), sometimes known as the Ufimtsev Defence or Yugoslav Defence, is a chess opening characterised by Black responding to 1.e4 with 1...d6 and 2...Nf6, followed by ...g6 and ...Bg7, while allowing White to establish an impressive-looking centre with pawns on d4 and e4...

. Unless transposition is reached, there are four popular, independent continuations:

• 3.g3 (the Przepiorka variation, closely related to the Fianchetto Variation of the King's Indian)
• 3.Bg5 (the Torre
  Carlos Torre Repetto
  Carlos Torre Repetto was a chess grandmaster from Mexico.Torre won the Louisiana championship at New Orleans 1923. He was first at Detroit 1924, followed by Samuel Factor, Herman H. Hahlbohm, Norman Whitaker, Samuel Reshevsky, etc., and at Rochester 1924...
  
   system, which may be considered a variant of the Torre Attack
  Torre Attack
  The Torre Attack is a chess opening characterized by the moves:The opening is named after the Mexican grandmaster Carlos Torre Repetto. The variation was also employed by Savielly Tartakower, and the young Tigran Petrosian on occasion...
  
  )
• 3.Bf4 (the London system)
• 3.Nc3 (the Barry Attack)

The Encyclopaedia of Chess Openings

Encyclopaedia of Chess Openings

The Encyclopaedia of Chess Openings is a classification system for the opening moves in a game of chess. It is presented as a five volume book collection describing chess openings...

classifies the East Indian Defence under A49 for the Przepiorka variation and A48 for the others.