Welcome to the real-world of cryptography! The book you’re holding in your hands (if you chose to acquire a printed version) is split into two equal parts of eight chapters. By going through all of it, you will learn (almost) all there is to know about cryptography in the real world—the one you’re standing in.
Note that the first part of the book was written to be read in order, although each chapter should tell you what the prerequisites are, so do not view this as a mandatory constraint. The first eight chapters take you through the basics—the building blocks of cryptography. Each chapter introduces a new ingredient and teaches you what it does, how it works, and how it can be used with other elements. This first part is all about giving you good abstractions and insights before we start making use of it all in the second part of the book.