This is the Grunfeld Defense...
		
		
	 
	
		
			To reach it: White moves this pawn forward
		
		
	 
	
		
			Black responds by moving his Knight
		
		
	 
	
		
			White then moves this pawn forward two squares
		
		
	 
	
		
			Black counters by playing this move (to put bishop on long diagonal)
		
		
	 
	
		
			Then when White develops his Knight...
		
		
	 
	
		
			Then Black claims stake in the center