A flank opening is a chess opening played by White and typified by play on one or both flanks (the portion of the chess board outside the central d and e files). White often plays in hypermodern style, attacking the center from the flanks with pieces rather than occupying it with pawns. Some of these openings are played often, although more often by advanced players than beginners, and 1.Nf3 and 1.c4 trail only 1.e4 and 1.d4 in popularity as opening moves.