In anatomical terms, handedness is the side of the body, and in particular the hand, that is most used in motor tasks. Most people are right-handed and few are truly ambidextrous (either-handed). In the brain, the paths for sensory and motor information are crossed, so the right side of the body is controlled by the left cerebral hemisphere and vice versa. The left hemisphere is usually dominant and also contains centers for speech and calculation. The non-dominant side deals with aspects of visual and spatial relationships, while other functions are represented on both sides. In some left-handed people, the right hemisphere is dominant. Suppression of left-handedness may lead to speech disorder. (wrist bones), metacarpals (in the palm), and phalanges (finger bones).

Handedness in chemical molecules is known as chirality.