  Many physical systems can be studied as collections of particles embedded in
space, evolving through deterministic evolution equations. Natural questions
arise concerning how to characterize these arrangements - are they ordered or
disordered? If they are ordered, how are they ordered and what kinds of defects
do they possess? Originally introduced to study problems in pure mathematics,
Voronoi tessellations have become a powerful and versatile tool for analyzing
countless problems in pure and applied physics. In this paper we explain the
basics of Voronoi tessellations and the shapes they produce, and describe how
they can be used to study many physical systems.
