Glauber modeling in high-energy nuclear collisions

We review the theoretical background, experimental techniques, and phenomenology of what is known in relativistic heavy ion physics as the Glauber model, which is used to calculate geometric quantities. A brief history of the original Glauber model is presented, with emphasis on its development into the purely classical, geometric picture used for present-day data analyses. Distinctions are made between the optical limit and Monte Carlo approaches, which are often used interchangeably but have some essential differences in particular contexts. The methods used by the four RHIC experiments are compared and contrasted, although the end results are reassuringly similar for the various geometric observables. Finally several important RHIC measurements ore highlighted that rely on geometric quantities, estimated from Glauber calculations, to draw insight from experimental observables. The status and future of Glauber modeling in the next generation of heavy ion physics studies is briefly discussed.