A system of electrical components and conductors through which electrical current flows is known as a circuit, or an electronic circuit. Some of the different components which can be a part of circuits are transistors, inductors, capacitors, resistors and diodes. There are a variety of operations which can be performed through the use of circuits such as amplifying signals and moving data. Circuits can either be constructed of individual connected wires or the interconnections can be made upon laminated substrates using photolithographic techniques. Some of the different types of circuits which are used to test new designs are perfboards, breadboards and stripboards. These circuits are easy to redesign, making it easy for designers to make changes quickly. This book discusses the fundamentals as well as modern approaches of circuits and their systems. It will serve as a valuable source of reference for graduate and post graduate students. The book is appropriate for students seeking detailed information in this area as well as for experts.