This book is an attempt to fill the gap between practitioners and theoreticians, and make the modeling and analysis of system performance more methodical and more realistic. It provides a cohesive introduction to the modeling and analysis techniques. A lack of system knowledge may not handicap the reader in digesting the material, successful application of these techniques to actual modeling requires a great deal of system knowledge. The problem of mapping a given or hypothetical system onto a model is as important as solving the model itself. In order to formulate the real system into an abstract form, one must be knowledgeable about which models are mathematically tractable, and how sensitive model solutions will be to specific assumptions and approximations introduced.