`Watchdog Timer` implementation on an Arduino

I am new to programming the arduino and have this query. Can a watchdog timer be implemented on the arduinos? Is there a library or function for the same?

You can have a watchdog timer on an Arduino. There may be exceptions. I don't know if there's a library. The core has this file: hardware/tools/avr/avr/include/avr/wdt.h. You can find some useful examples of how to use the watchdog here: http://gammon.com.au/power.