The Scheveningen Variation is a chess variation of the Sicilian Defence.
Keep in mind that Black does play sometimes first 2...e6 (not d6) and later on d6 which reaches the same chess position by transition.
Black has the center-pawn-formation e6 and d6, which controls vital center squares on d5 and e5 and has the half-open c-file. He initiates active play on the queenside and along the c-file against the backward c-pawn of white. At the right moment he can make a break in the center with moves like ...e5 or...d5 changing the character of play in the center.
The most aggressiv line is the Keres-Attack which starts a kingside attack with 6. g4. However, other possible moves for white are: 6.Be2, 6.f4, 6.Be3, 6.Bc4, 6.g3 and 6.f3.(f3-prepares the English Attack with Be3, Qd2 and g4)
The usual classical moves of White are Be2, O-O, f4, Kh1 and now the plan, Qe1 followed by Qg3, activating the queen.
This opening is very complex and gives Black very good counter chances and creative play. It has been played by many chess grandmasters.