A bipod is a support device that is similar to a tripod

Tripod

A tripod is a portable three-legged frame, used as a platform for supporting the weight and maintaining the stability of some other object. The word comes from the Greek tripous, meaning "three feet". A tripod provides stability against downward forces, horizontal forces and moments about the...

 or monopod

Monopod

A monopod, also called a unipod, is a single staff or pole used to help support cameras, video cameras, binoculars, rifles or other precision instruments in the field.-Camera and imaging use:...

, but with two legs. It provides significant stability along two axes of motion (side-to-side, and up-and-down).

Firearms

On firearms, bipods are commonly used on rifles to provide a forward rest and reduce motion. They are also seen on other long-barrelled weapons. The bipod permits the operator to rest the weapon on the ground, a low wall, or other object, reducing operator fatigue and permitting increased accuracy. Bipods can be of fixed or adjustable length. Some can be tilted and also have their tilting point close to the bore central axis, allowing the weapon to tilt a little left and right, allowing a quick horizontal sight picture on uneven ground and keeping the operator close to the ground. Bipods are for the most part folded away forward, not back towards the shooter, and sometimes fold into vertical foregrips.

Some bipods used for rifles allow the rifle to swivel or "hang" near its bore axis, offering a more stable shooting position with large and heavy aiming optics mounted.