Computer simulation is increasingly used in physics and engineering to predict the probable outcome of experiments and to aid in their interpretation. The methods of simulation are based on a range of numerical techniques for treating ordinary and partial differential equations. Since much of physics can be broken down into a relatively small set of fundamental equations, there is a set of very general methods which can be widely applied. This text aims to give an introduction to those methods suitable for readers at an undergraduate level and those meeting the subject for the first time at postgraduate level. The methods are illustrated with simple programs and problems. The book covers a range of material t available in a simple form in a single text elsewhere.