In American football and Canadian football to tackle is to physically interfere with the forward progress of a player in possession of the ball, such that his forward progress ceases and is not resumed, or such that he is caused to touch some part of his body to the ground other than his feet or hands, or such that he is forced to go out of bounds. In any such case, the ball becomes dead, the down is over, and play ceases until the beginning of the next play. A tackle is known as a quarterback sack when the quarterback is tackled behind the scrimmage line. Tackle is also the name of player positions on both the offensive and defensive teams. Usually there is a left and right tackle on each team.
In Rugby football the tackle is similar in that it is done by bringing the player with the ball to the ground by holding on to them. The tackled player must release the ball, but the ball is not dead and play continues.
In soccer a player tackles an opponent by taking control of the ball from them. Play continues following a tackle.