At this point black must decide how to face white's aggression. Traditionally, the two most popular replies are [[/1...d5/]] and [[/1...Rf6/]]. Other moves tend to allow white a broad center with 2. e4. Allowing the broad center was frowned upon in classical times, but is more of a matter of preference today. Another reason [[/1...d5/]] and [[/1...Rf6/]] are the main replies considered is that many of the alternatives transpose into main lines anyway. One notable exception is the Dutch Defense: [[/1...f5/]] whose character is unique and prevents 2. e4. [[/1...d5/]] directly challenges white's plan to establish a broad center. [[/1...Rf6/]] prevents an immediate 2. e4 while maintaining flexibility to play a number of "Indian" systems or move back into a system typical of [[/1...d5/]].
