The umpires signal various events with gestures, as follows:
When a batsman is out, the umpire making the decision raises one hand above his head, with the index finger extended.
There is no formal signal to indicate that a batsman is not out. The umpire can either shake his head 'no' or not signal at all.
A four scored by the ball reaching the boundary is signalled by an arm extended horizontally and waved briefly back and forth in a horizontal arc.
A six is signalled by raising both arms straight over the head.
A no ball is signalled by holding an arm out horizontally.
A wide is signalled by holding both arms out horizontally.
Runs scored as byes are signalled by raising one arm over the head, palm open.
Leg byes are signalled by raising one leg and tapping the knee with one hand.
If the umpire has to signal dead ball to prevent the players from assuming that the ball is still alive, he waves both arms across each other in front of his abdomen.
One short is signalled by touching the tip of one hand to the same shoulder.