The heaviness of an item is its weight. It is proportional to the item's gravity multiplied by its constant mass. Due to differences in gravity, the weight of an object at the summit of a mountain will be less than the weight of the same object at the base. The newton is a unit of measurement for weight. A newton accounts for an object's mass and relative gravity to determine its total force, which is weight. Although mass and weight are distinct concepts, the process of ascertaining both is referred to as weighing.