This document provides an introduction to AVR microcontrollers. It discusses the history of microcontrollers beginning in 1971 and components like CPU, ROM, RAM and I/O. AVR microcontrollers were introduced in 1996 and range from 1 to 256KB with 8 to 100 pins. They are cheaper and slower than microprocessors but are useful for specialized applications. The document outlines the AVR architecture and family as well as development tools and support for AVR microcontrollers.