What is a watchdog timer and why is it important?

A watchdog timer (WDT) is a hardware timer that resets the microcontroller if not periodically refreshed by software. The program must 'kick' or 'feed' the watchdog regularly; if the program hangs or crashes and fails to do so, the watchdog times out and triggers a reset, recovering the system. Watchdogs are essential for reliability in embedded systems, especially autonomous devices where manual reset is impractical. Configuration includes timeout period, reset action, and window mode (prevents too-frequent kicks).