This book is a collection of different essays on economic studies. It contains seven parts with fourth two essays. Each part deals with an advanced topic in economic. Part one: History of economic thought, Part two: Money and banking, Part three: The theory of the firm. Part four of this book is titled: Trade cycle, Part five of this book the economic history, Part six: Applied economics, and finally Part seven: Public choice. The book is useful for different types of readers, for example post graduate students in economics and business management, it will help them to understand the advanced topics of economics, for lecturers to prepare their lecture notes, for other readers who are willing to explore the world of economic science.