The purpose of this chapter is to set the stage for the book and for the upcoming chapters. We first overview classical information-theoretic problems and solutions. We then discuss emerging applications of information-theoretic methods in various data-science problems and, where applicable, refer the reader to related chapters in the book. Throughout this chapter, we highlight the perspectives, tools, and methods that play important roles in classic information-theoretic paradigms and in emerging areas of data science. Table 1.1 provides a summary of the different topics covered in this chapter and highlights the different chapters that can be read as a follow-up to these topics.

In this chapter, we have provided an overview of ambient backscatter communication systems. Firstly, we have introduced the fundamentals of modulated backscatter and its three main configurations, i.e., monostatic, bistatic, and ambient backscatter communication systems. Then, key channel-coding and modulation techniques in modulated backscatter communication systems are discussed. Two major types of backscatter communication channels and their link budgets are also introduced. Next, theoretical analyses and experimental measurements of backscatter channels are reviewed. Finally, we have discussed some research challenges of backscatter communication systems, especially ambient backscatter communication systems.