Cognitive behavioral therapy is a form of psychological treatment that has developed through a set of approaches sharing a common basic model of cognition and behavior, playing an important role in understanding and alleviating the burden of psychological problems. While early forms of this therapy focused on modifying observable behavior, later versions emphasized cognitive processes. More recently, third-wave approaches have shifted from focusing on the content of an individual's thoughts to their relationship with those thoughts and the underlying processes of thinking. This book provides an overview of what cognitive behavioral therapy is, its origins, its role, and its applications, and explores how one of the driving forces behind the success and ongoing development of this therapy lies in its empirical foundation, and how its continuous evolution is essential for meeting future challenges.