In Cricket,is the action of propelling the ball toward the wicket,the bowler mainly do it to take wicket or stop the
Cricket Right-Arm Medium by Philadelphian Bart King

American Cricketer,Bart King relasing a right-arm ball

Batsman from scoring.A person which is skilled with bowling or mainly does bowling is called a bowler and a bowler who is also a Batsman is a  All-Rounder.

There are different types of bowlers ranging from fast bowlers, whose primary weapon is pace, through swing and seam bowlers who try to make the ball deviate in its course through the air or when it bounces, to slow bowlers, who will attempt to deceive the batsmen with a variety of flight and spin. A spin bowler usually delivers the ball quite slowly and puts spin on the ball causing it to bounce at an angle off the pitch.

If a bowler's foot steps infront of the bowling crease line during the run-up or whenever the player is about to bowl the ball and hasn't been thrown then its no-ball and gives a extra run to the other team and gives them a free-hit in the next-ball and they can't get out on free-hit unless run-out and if they hit a six or four or have taken any runs on that ball then then it will give them a extra-run as a addition to that run,if the bowler bowls over the waist of the batsman,then its a beamer,in beamer they will only get a run and won't get a free-hit unlike normal no-ball and if the ball has gone to high then its wide and if its too away from the batsman,then also its wide and if it goes for a wide and no batsman and a fielder can get it and it goes for four then it gives 5 runs.