An Atom is the fundamental representation of state in the Movable Feast Machine, in some ways analogous to an object in an object-oriented language. Each site is occupied by exactly one atom at all times (because even empty is considered a kind of Atom). An Atom has a type number that links it to the element of which it is an instance. In addition to its type number, each an Atom possesses a very small amount of mutable storage (on the order of a few dozens of bits perhaps) which may be defined as desired by the element and modified during an event.