Depth perception is the ability of the eye to see in three dimensions. This is possible as the two eyes form separate images of the same object on the retina, and then the brain combines the two images to form one single image.
The two separate images are formed as the two eyes are about two inches apart. There is a common field of view between the two eyes.
Depth perception allows the brain to perceive the size and distance of objects relative to other objects. This is far more important for objects that are very close to the eyes. For distant objects, lack of depth perception is less obvious. The brain also uses previous information related to size of known objects.
Depth perception is often referred to as binocular stereoscopic vision or stereopsis.