The key components of a microcontroller include a central processing unit (CPU), memory (both RAM and ROM), and input/output peripherals. The CPU executes instructions, while memory stores program data and instructions. Additionally, a microcontroller often incorporates timers, analog-to-digital converters (ADCs), and communication interfaces like UART or I2C to interact with other components. These integrated features make microcontrollers essential for embedded systems in various applications, such as home automation, robotics, and consumer electronics.