This book is meant to be used as a textbook in a junior-or senior-level undergraduate course on stochastic models. The students are expected to be undergraduate students in engineering, operations research, computer science, mathematics, statistics, business administration, public policy, or any other discipline with a mathematical core. Students are expected to be familiar with elementary matrix operations (addition, multiplication, and solving systems of linear equations, but not eigenvalues oreigenvectors), first-year calculu s (derivatives and integrals of simple functions, but not differential equations), and probability. The necessary material on probability is summarized in the appendices as a ready reference.