A dangerous penalty usually penalized harshly due to the skate blade and the potential for severe injury if it is to an opponent's body. Kicking of the puck is allowed, but cannot be used as a way of propelling the puck into the net for a goal.
Players can kick the puck to pass or play defense, but they cannot kick other players, step or push off on them in any way. If so, they usually will receive a match penalty and at the very least a major penalty for incidental kicking.
Players are quite careful, especially at the National Hockey League - NHL to avoid kicking or even stepping on other players usually. However, one of the most heavily suspended and infamous kicking violations occurred in 2007 when the New York Islanders' Chris Simon stomped on Jarkko Ruutu of the Pittsburgh Penguins resulting in a 30-game suspension.
One of the common reasons for reviewing whether goals should be disallowed is sometimes due to the possibility of a player kicking the puck into the net. Although it is legal to kick the puck, a goal cannot be the result of kicking the puck into or off another player. Review officials will usually be seeing if a "distinct kicking motion" has occurred, in which case the goal would be disallowed.