Bogo-Indian Defense

The Bogo-Indian Defense arises after White plays d4, c4, and Nf3 while Black answers with ...Nf6, ...e6, and ...Bb4+. The check means that the bishop on b4 attacks White's king along the diagonal. White must answer the check, usually by blocking it with a piece.

Black develops a piece while forcing White to answer the check, so White must define part of the setup immediately. Black may then exchange the bishop, retreat it, or keep it on b4 depending on White's response. The position usually continues with piece pressure on the center and later pawn advances such as ...d5 or ...c5.

The Bogo-Indian check forces a development choice

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StartBb4+Bd2

...Bb4+ develops a piece with tempo and forces White to choose how to interrupt the diagonal.

Nf3 leaves the diagonal to the king open

With no knight on c3, Black's bishop can reach b4 with check instead of creating the Nimzo-Indian pin.

1. ...Bb4+ develops a piece with tempo and forces White to choose how to interrupt the diagonal.

It is closely related to the Nimzo-Indian Defense. The essential difference is White's knight placement: in the Nimzo-Indian the knight is on c3 and Black's bishop pins it to the king, meaning it cannot move without exposing the king; in the Bogo-Indian the knight is on f3 and ...Bb4+ gives check. It also shares many structures with the Queen's Indian Defense.