The document discusses interrupts in microcontrollers. It defines interrupts as a way to asynchronously process events outside the main program flow. When an interrupt occurs, the microcontroller finishes its current instruction, saves context to the stack, and jumps to the interrupt service routine (ISR) before returning to the main program. The document outlines the interrupt sequence and describes how to define an ISR. It also discusses interrupt priorities, nesting, and the registers used to configure and manage interrupts.