Local structure characterization in particle systems

Many tools and techniques measure local structure in materials in contexts ranging from biology to geology. We survey the tools and metrics that are especially useful for analyzing particulate soft matter. The metrics we discuss can all be computed from the positions of the particles, and are thus most useful when there is access to this information, either from simulation or experimental imaging. For each metric, we provide derivations, intuition regarding its implications, example uses, and references to software packages that compute the metric. Our survey encompasses characterization techniques ranging from the simplest to the most complex, and will be useful for readers getting started in the structural characterization of particle systems.