Transistor technology has undergone major developments in the last ten years. Most of the disadvantages of the devices have either been eliminated completely or drastically reduced. The much improved device characteristics have enabled the theory of the operation of transistor circuits to be substantially simplified by approximations that introduce relatively small errors. (The meaning of magnitude of these errors is discussed in this text). Using modern analysis techniques coupled with simplified equivalences, the book relies on basic circuit theory, KVL, KCL and Thevenin's equivalence. Voltage and current laws are used directly in the examination of devices, giving more insight into circuit performance. The need to memorize formulae is practically eliminated.