In Chapter 1 we covered basic electronics and elementary circuit components such as resistors, capacitors, inductors, transformers, and simple semiconductors. In this chapter we expand these topics and introduce new ones so as to provide a basic background in digital electronics and in the electronic circuits that are often used in microcontroller-based systems. The chapter also contains information on some of the simpler electronic devices often found in electronic circuit boards, such as diodes, LEDs, and logic gates. Chapter 6 covers other circuit components including switches, seven-segment displays, LCDs (liquid crystal displays), buzzers, motors, and flip-flops.