The voter model is a simple mathematical model of opinion formation in which voters are located at the nodes of a network, each voter has an opinion (in the simplest case, 0 or 1, but in the general case, n), and a randomly chosen voter assumes the opinion of one of its neighbors. This model can be used to describe the phase transition behavior of idealized physical systems and can result in a rather remarkable amount of structure starting from a given "random" input." It can be modeled very easily using cellular automata. It turns out that in finite networks (i.e., any real model), fluctuations always cause the system to reach an "absorbing" (i.e., constant) state.