Performance evaluation is a critical stage of software- and hardware-system development that every computer engineer and scientist should master. Although complex Рrequiring skills in mathematics, measurement techniques and simulation Рperformance evaluation is primarily an art; indeed, the most difficult stage in a performance analysis is defining the approach: once you know what to do, it is less difficult to define a plan of attack with your familiar software tools. We present a set of topics, which we believe should be part of every engineer's intellectual toolkit. This includes the statistical exploitation of numerical results in an efficient and ethical way, for example: how to summarize variability or fairness; what transient removal in a simulation is; and how to make predictions from a time series. We also present well-known performance patterns, which helps to quickly bring the engineer to the main issues. For queuing theory, we focus on a subset of very useful results, such as operational laws. A highlight of the book is the development of Palm calculus, also called “the importance of the viewpoint,” which is central to queuing theory. Indeed, this topic has so many applications to simulation and to system analysis in general that it is a very good time investment. This book began as a set of lecture notes for a course given at EPFL.