A moment is a mathematical expression involving the product of a distance and a quantity such as a physical force, magnetic force, electric charge or a velocity. Moments are usually defined with respect to a fixed reference point and refer to physical quantities located some distance from the reference point. For example, the moment of force, often called torque, is the product of a force on an object and the distance from the reference point to the object. In principle, any physical quantity can be multiplied by a distance to produce a moment. Commonly used quantities include forces, masses, and electric charge distributions involving spherical harmonics, a list is provided later.