The main audience for this book will be experienced system administrators of null-to-medium expertise with cfengine, although more advanced cfengine users may also find useful snippets and techniques. The goal of the book is to serve as a complement to the existing reference guides, not describing every single aspect of cfengine configuration but rather tracing a path through it with examples and techniques that can be put to work straight away. CFEngine is used by many companies that manage large datacenters, including Google, IBM, Facebook and HP. A large number of system administrators, by choice or by mandate, are getting introduced to cfengine in recent times, and they are looking for a good practical guide to the topic. Let us provide it to them.