This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book attempts to organize in one place the mathematics, probability, statistics, machine learning, and text processing information that is required for a practitioner of cyber security analytics, as well as the basics of cyber security needed for a practitioner. It focuses on the idea of a model is central to the aspects of Artificial intelligence and machine learning. The book explains non parametric methods that relax assumptions about the underlying distribution of the data rather than parametric methods that posit a particular parametric family for the distribution. It also focuses on techniques related to data, and to the types of problems that can be addressed through data analysis and machine learning methodologies.