The Modern Defense is a chess opening in which Black allows White to occupy the center with pawns on d4 and e4. Black's hope is to attack and undermine White's "ideal" position without directly attempting to occupy the center himself. A typical move order for the Modern Defense is 1.e4 g6 2.d4 Bg7.
The Modern Defense is quite closely related to the Pirc Defense, to the extent that the "Modern" is often seen as a description of some variants of the Pirc; the primary difference between the two openings is that in the Modern Black delays developing his knight to f6.
