Performance evaluation is a critical stage of software- and hardware-system development that every computer engineer and scientist should master. Although complex – requiring skills in mathematics, measurement techniques and simulation – performance 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 ¬ìthe importance of the viewpoint,¬î 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.