Franek (McMaster U.) reminds us that programs are not executed in a vacuum but in a computer memory, a simple fact that changes the way must programmers and students must think about the semantics of the programming language. He begins by describing the transformation of a source file to an executable module, the work of variables as "data containers," the dynamic allocation and de-allocation of memory, functions and function calls, one-dimensional arrays and strings, multi-dimensional arrays, classes and objects, linked data structures, leaks and their debugging, and programs in execution expressed as processes and threads. He includes a glossary and a web site to obtain the lengthier examples of code.