Traditionally, a vade mecum (pronounced ‘‘VAHdee MAYkem’’) is a laboratory manual that guides the student step by step through complex procedures. Operating systems are complex mixtures of policy and mechanism, of algorithm and heuristic, and of theoretical goals and practical experience. This vade mecum tries to unify these diverse points of view and guide the novice step by step through the complexities of the subject. As a text, this book is intended for a first course in operating systems at the undergraduate level. The subject has so many individual parts that its practitioners and teachers often concentrate on subareas and ignore the larger concepts that govern the entire subject. I have tried to rectify that situation in this book by structuring the presentation about the dual ideas of resource management and beautification.