Chess Opening Theory/1. d4/1...d5/2. Bg5

=Levitsky Attack or Queen's Bishop Attack=

2. Bg5
Bg5 is an immediate attack by white, in hopes of slowing black's development via pinning the pawn on e7. This position can be negated by black developing Nf6, or a pawn move f6. usually, the bishop cannot remain in its position for long, necessitating a loss of tempo.

Theory table
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'''1. d4 d5 2. Bg5'''

Black's main options are: