This chapter discusses various aspects of queuing theory and also discusses various methods that can be used to determine whether a certain statistic or distribution appropriately describes an observed process. The use of queuing analysis provides us with a set of techniques for calculating quantities and the effects of coupled and closed networks of queues. The chapter looks at analytical modeling in general, at the characteristics of the systems that we are interested in modeling, and at the suitability of queuing models in general and their use in particular. It outlines several methods for estimating the statistics of a distribution that describes the real world process. The chapter explores several techniques for estimating the parameters of distributions and looks at some methods for finding a distribution that fits the sampled data. It covers the areas from stochastic processes to queuing theory to basic estimation, span a wide range of topics, each with a wealth of specialities and techniques.