Scoring runs is the subject of Law 18 in the Laws of cricket.
The act of running is unnecessary if the batsman hits the ball to the marked boundary of the field. If the ball reaches the boundary having made contact with the ground, four runs are automatically added to the scores of both the batsman and the team. If the batsman succeeds in hitting the ball over the boundary on the full (i.e., the ball does not make contact with the ground until it is beyond the boundary), six runs are added. Batsmen frequently run singles and also "twos" and "threes". If the batsmen run a single or a three, they effectively exchange positions, so the striking batsman becomes the non-striker for the next delivery, and vice versa. If the single or three is scored off the last delivery of the over, the striker having changed ends retains strike for the first delivery of the next over. There are rare instances of "fours" being all run when the ball does not reach the boundary. A "five" is possible but would almost certainly need the assistance of a mistake by the fielders, such as an overthrow. In certain situations, a five can be awarded as "penalty runs". The batsman is never compelled to run and can deliberately play without attempting to score; baseball's force out rule has no equivalent in cricket.
The batsmen stop running when the ball is being returned to either the bowler or the wicketkeeper. In addition to runs, the team total is incremented by , also known as "sundries", which are awarded as a form of penalty against the fielding side, either because the bowler has broken the rules or because the fielders have failed to control a loose ball which did not make contact with the bat. Extras are not added to the batsman's individual score.
If, when attempting to turn for an additional run, one of the batsmen fails to ground his bat behind the popping crease, the umpire declares a "short run" and this is not added to the score. The umpire can, at his discretion, warn the batsman if he considers a short run to have been a deliberate act. In that event, the umpire will cancel all runs made following the last delivery and will instead impose a five-run penalty on the batting team, reducing their score by five: this is an extreme course of action that is rarely undertaken. If the bat is dropped as the striker turns to complete a run, that run will not count.
Sixes and fours are automatic, there is no need to run if they deem the ball will surely touch or go past the boundary rope. If the batsmen decide to run, they will be cancelled off, and four/six runs will be added to the score.