A type of duplex receptacle or circuit breaker that breaks the circuit when it detects a dangerous electrical arc in order to prevent electrical fires.  They can sometimes be combined with Ground Fault Circuit Interrupters (GFCI) into one device.  AFCI's have become required equipment in most locations of a building throughout North America. Check your local jurisdiction for the current requirements for your application.  Zero Surge technology does not interfere with the operation of AFCIs.