This chapter introduces the fundamental questions and concepts surrounding economic growth and development. It begins by highlighting the significant income differences across countries, emphasizing that the richest countries are over thirty times richer than the poorest. The chapter discusses the welfare implications of these differences, noting that higher income levels are associated with better living standards, consumption, and health. It also explores the relationship between economic growth and income differences, explaining that the divergence in income per capita has been significant over time, with much of the divergence occurring during the 19th and early 20th centuries. The chapter further examines the origins of today's income differences, attributing them to the "takeoff" period in Western Europe and its offshoots around 200 years ago. Finally, it introduces the concept of conditional convergence, which suggests that the income gap between countries with similar characteristics tends to close over time. The chapter concludes by setting the stage for more advanced models and theories that will be discussed in subsequent chapters.This chapter introduces the fundamental questions and concepts surrounding economic growth and development. It begins by highlighting the significant income differences across countries, emphasizing that the richest countries are over thirty times richer than the poorest. The chapter discusses the welfare implications of these differences, noting that higher income levels are associated with better living standards, consumption, and health. It also explores the relationship between economic growth and income differences, explaining that the divergence in income per capita has been significant over time, with much of the divergence occurring during the 19th and early 20th centuries. The chapter further examines the origins of today's income differences, attributing them to the "takeoff" period in Western Europe and its offshoots around 200 years ago. Finally, it introduces the concept of conditional convergence, which suggests that the income gap between countries with similar characteristics tends to close over time. The chapter concludes by setting the stage for more advanced models and theories that will be discussed in subsequent chapters.