Publisher Summary This chapter explores the world of embedded systems in today's scenario, which has one or multiple computers inside it which work like the core controller of all functions. The embedded computer inside is actually a small microcontroller, which is a type of microprocessor designed and adapted to control embedded applications. It consists of microprocessor core, memory, and peripherals, whose features are easy to understand. However, this is quite unlike working with a desktop computer used for word processing or computer-aided design, where the internal workings are skillfully hidden from the user. The microchips, as this chapter outlines, can have a huge range of microcontrollers wherein they can be differentiated into different families. The 8- bit PIC family can be divided three categories: baseline, that are ideal for really tiny applications; mid-range, that contains several simple but important developments, when compared to the baseline device; and high-performance, where Microchip has come to grips with some of the issues of sophisticated processors. These vary in instruction of word size, stack size, number of instructions, and interrupt vectors. Each segmented family has a similar structure and distinct set. The chapter reviews microprocessors and microcontrollers separately and notes that although there are commonalities in the family of microcontrollers, the knowledge of one type builds on the knowledge of the other. To begin with the simplest of the microcontrollers can be a good example to understand the features of its architecture. The basic one may be a good microcontroller for learning the general features, specifically PIC microcontrollers.