Written for readers interested in non-thermal gas discharge plasmas and their applications, this book is focused on microwaves and microwave generated plasmas which can be used in a number of applications. Even within the engineering community, there is a very little knowledge about different plasma systems and applications even though there is now growing interest in such technology for new plasma chemical processes. This book includes detailed descriptions, explanations and recommendations in three parts of the technology: (1) the microwave power and components, (2) the plasma properties and generation principles, (3) selected applications. Chapter 1 is devoted to microwave systems starting with descriptions and explanations of parts and components in microwave power lines, which can be used not only in laboratory experiments but also in industrial devices. Chapter2 contains fundamentals of gas discharge plasma and differences between plasmas generated at different kinds of power, with particular emphasis to microwave power. Chapter 3 is devoted to plasma processing and explanations of plasma interactions with solid surfaces and gases, particularly at reduced and low pressures. Chapter 4 is focused on different microwave plasma systems, including novel and non-conventional ones developed and tested in different processing applications at reduced pressures. Chapter 5 covers microwave plasma systems and applications at atmospheric and higher pressures, including plasmas inside liquids and plasma interactions with the combustion flames. Chapter 6 describes new trends in microwave discharges with future perspectives of the microwave plasma and its applications.