A run out is a way of getting a batter out in cricket. It involves hitting a wicket with the ball when no batsman is in the ground of that wicket; the batsman who is out is the one who is nearest to that ground, or if both batsmen are in a ground, the batsman who reached that ground second. Run outs can happen when batters are trying to score runs by running between the two grounds.
When a bowler is readying himself to bowl, the ball becomes live; if the nonstriker leaves the ground at the bowler's end before the bowler has thrown the ball, then the bowler can hit the wicket in this ground with the ball to "mankad" the nonstriker.
A stumping is a special type of run out in which the wicketkeeper (the fielder with gloves behind the striking batter) hits the wicket in the ground at the striker's end with the ball when the striker is out of that ground.
Stumpings are not allowed on no-balls; a striker who is not trying to run can only be run out on a no-ball if the wicketkeeper has another fielder help him.