The bridge (also called gymnastic bridge) is an exercise. Many variations of this exercise are employed throughout the world, most commonly the balancing of the body on the hands and the feet. It is intended to improve lower back and gluteus strength.

The bridge is frequently compared to the deadlift in terms of which muscles the exercises work, and as such the bridge could be considered the bodyweight exercise equivalent to the weight training deadlift. Just like its weight training counterpart, the bridge primarily works muscles which are part of the posterior chain, but also many important muscles of the anterior chain.

More Info: en.wikipedia.org