1. Number of balls
The ball shall be bowled from each wicket alternately in overs of 6 balls.

2. Start of an over
An over has started when the bowler starts his run up or, if he has no run up, his delivery action for the first delivery of that over.

3. Call of Over
When 6 balls have been bowled other than those which are not to count in the over and as the ball becomes dead - see Law 23 (Dead ball) - the umpire shall call Over before leaving the wicket.

. Balls not to count in the over
(a) A ball shall not count as one of the 6 balls of the over unless it is delivered, even though a batsman may be dismissed or some other incident occurs before the ball is delivered.
(b) A ball which is delivered by the bowler shall not count as one of the 6 balls of the over
(i) if it is called dead, or is to be considered dead, before the striker has had an opportunity to play it. See Law 23 (Dead ball).
(ii) if it is a No ball. See Law 24 (No ball).
(iii) if it is a Wide. See Law 25 (Wide ball).
(iv) if it is called dead in the circumstances of either of Laws 23.3 (vi) (Umpire calling and signalling Dead ball) or 42.4 (Deliberate attempt to distract striker).

5. Umpire miscounting
If an umpire miscounts the number of balls, the over as counted by the umpire shall stand.

6. Bowler changing ends
A bowler shall be allowed to change ends as often as desired, provided only that he does not bowl two overs, or parts thereof, consecutively in the same innings.

7. Finishing an over
(a) Other than at the end of an innings, a bowler shall finish an over in progress unless he is incapacitated, or he is suspended under any of Laws 17.1 (Practice on the field), 42.7 (Dangerous and unfair bowling - action by the umpire), 42.9 (Time wasting by the fielding side), or 42.12 (Bowler running on the protected area after delivering the ball).
(b) If for any reason, other than the end of an innings, an over is left uncompleted at the start of an interval or interruption of play, it shall be completed on resumption of play.

8. Bowler incapacitated or suspended during an over
If for any reason a bowler is incapacitated while running up to bowl the first ball of an over, or is incapacitated or suspended during an over, the umpire shall call and signal Dead ball.
Another bowler shall complete the over from the same end, provided that he does not bowl two overs, or parts thereof, consecutively in one innings.