The major of the book is a detailed discussion of various aspects of the design of simulation programs illustrated by the discussion of almost 100 code examples using the C programming language for execution under Unix and the X-Window system. The discussion is based on the program aw. The source code, manual, and tutorial for this program is available on http://www.fysik.dtu.dk/camp-sd.html. Graduate level textbook and a reference for simulation practitioners in physics, chemistry, biology, and engineering.