When bowling the ball, the bowler's back foot in his "delivery stride" must land within the two return creases while his front foot must land on or behind the popping crease. If the bowler breaks this rule, the umpire calls "No ball".
The importance of the popping crease to the batsman is that it marks the limit of his safe territory for he can be stumped or run out (see Dismissals below) if the wicket is broken while he is "out of his ground".
Pitches vary in consistency, and thus in the amount of bounce, spin, and seam movement available to the bowler. Hard pitches are usually good to bat on because of high but even bounce. Dry pitches tend to deteriorate for batting as cracks often appear, and when this happens spinners can play a major role. Damp pitches, or pitches covered in grass (termed "green" pitches), allow good fast bowlers to extract extra bounce. Such pitches tend to offer help to fast bowlers throughout the match, but become better for batting as the game goes on