|This article does not cite any references or sources. (July 2008)|
Bounding overwatch, also known as leapfrogging or simply bounding, is the military tactic of alternating movement of coordinated units to allow, if necessary, suppressive fire in support of offensive forward movement or defensive disengagement. 
As members of a unit (element to platoon level) take an overwatch posture, other members advance to cover; these two groups continually switch roles as they close with the enemy. This process may be done by "leapfrogging" by fireteams, but is usually done within fireteams along a squad/platoon battle line to simulate an overwhelming movement towards the enemy and make it more difficult for the enemy to distinguish specific targets.
This military tactic takes continuous training and focused coordination to be effectively practiced on the modern battlefield. It was first developed in World War II, when the prevalence of man-portable automatic weapons made suppressing fire possible.
Example: A squad (2 fireteams) in an urban combat zone must advance to a building 100 feet away, crossing an intersection they believe might be in enemy rifle sights from elevated buildings. If the team simply made a run-for-it, they expose themselves to potential enemy fire without protection.
This is where bounding overwatch comes into play.
One fireteam takes an overwatch position while the other team bounds (a bound is a 3–5 second rush) to a new covered position. This way there is always an overwatch team that can react instantaneously to enemy fire (the bounding team would have to stop, take cover, locate the enemy, and aim before they could return fire). Once the covered position is reached by the bounding team, they now assume overwatch positions while the other team then becomes the bounding team.
By using bounding overwatch, this unit is able to effectively move through a hostile urban street and intersection, without unnecessarily exposing themselves to enemy fire.
If enemy contact is made, the overwatch team opens fire and the unit takes up a process called Fire and Maneuver which is very similar to bounding overwatch in that teams alternate firing and maneuvering. During fire and maneuver, the commander takes more direct control of team movements and positions.