Protected area

Often incorrectly called the Danger area, the Protected area is an area of the pitch to be 'protected' by the umpires against damage by the bowler in his follow-through - the strides he takes while decelerating from delivering the ball.
While not usually marked, it is a rectangular strip running down the middle of the pitch from 5 ft (1.52 m) in front of the popping crease at either end and 1 ft wide (30.48 cm) either side of an imaginary line connecting the middle stumps at each end.
Thus the protected area is the section of the pitch on which most deliveries will bounce. Because accidental or, more importantly, deliberate damage to a cricket pitch can materially affect the characteristics of a ball bouncing on it, it is regarded as unfair play and penalised under the Laws of the game.
Bowlers must not run on to the protected area after bowling the ball. If the bowler strays onto this area without good cause, he is first of all cautioned, then for a second offence given a final warning and finally, if he persists, banned from bowling again in that innings.
When it comes to the pitch as a whole and the protected area in particular, the best general rule for all players is - wherever possible keep off that grass!