In this book, an introduction of polymer insulators has summered and presented in a simple way which can be quiet useful for any person who work in polymeric electrical insulators fields. This book can be meaningful for theoretical lessons for undergraduates and postgraduate students as well as for the researchers. It has three chapters, the first one covers the introduction of electrical insulators, with historical background, benefits and the role of electrical insulators in industry. The second chapter contains applications, types, and the main components in details and all output parameters of electrical insulators in a comprehensive explanation with schematic figures. The third chapter contains the explanation with more details about polymer insulators.