Crease (cricket)

In cricket, the creases are lines on the field that separate different areas of the field from each other. There are two popping creases (which are the main creases), return creases, and two bowling creases.
Popping creases.
The two popping creases extend across the field, and are 58 feet (about 20 meters) away from each other in the center of the field. They are the edges of the area between the two batsmen's grounds. 
Return creases.
The return creases define which parts of the field the bowler may bowl legal deliveries from; a no-ball is called when the bowler's back foot touches or goes over a return crease before he has released the ball.