If something is dorsal it is situated at or close to the back of the body or to the posterior part of an organ (from the Latin dorsum = the back). In an animal that walks on all fours, the dorsal surface is its back. By extension, in all vertebrates it is the surface along which the spine runs. In animals that walk on two legs, such as humans, it is therefore the surface that faces backward, or the posterior surface.

In human anatomy, the term "dorsal" is generally only applied to the hand and fingers, and the foot and toes, and in these cases refers to the upper surfaces (e.g., the "back" of the hand). The opposite is plantar or volar.