A bipod is a support device that is similar to a tripod or monopod, but with only two legs. It provides significant stability along two axes of motion. Bipods are commonly seen in use at the end of sniper rifles or other long barrel on firearms, especially machine guns. This is the result of the machine gun's ability to fire very long, sustained bursts. Such bursts causes significant recoil in the weapon, decreasing accuracy. By fitting a bipod on the frontal section of the weapon, the weapon can be put onto the ground (or some other object). This can significantly increase accuracy, as the man in charge of the weapon is no longer charged with the task of stablizing the weapon. A tripod refers to any three-legged structure. ... A unipod, also called a monopod, is a pole used to help support cameras (and more rarely binoculars). ... A coordinate axis is one of a set of vectors that defines a coordinate system. ... A U.S. Army soldier peers through a scope mounted atop his M-14 rifle during operations in Iraq A sniper rifle is a type of rifle used for engaging in the act of sniping, most purely a rifle used for shooting with great accuracy. ... The barrel of a firearm is the tube, usually metal, through which a controlled explosion is released in order to propel a projectile out of the end at great speed. ...