"GFCI" stands for ground-fault circuit interrupter, which is an inexpensive electrical device that, if installed in household branch circuits, could prevent more than two-thirds of the approximately 300 electrocutions still occurring each year in and around the home. Installation of the device could also prevent thousands of injuries each year from burns and electric shocks.
Currently, most jurisdictions require GFCI protection for every receptacle/outlet and motor connection in every location of habitable area, as well as areas where the environment might be wet, moist or damp. That means everywhere in a bathroom, all the countertop outlets in the kitchen, and within 6 feet of the sink at the wet bar. It also means everywhere outside.
Circuit-breaker and receptacle-type GFCIs may be installed in your home by a qualified electrician. Receptacle-type GFCIs may be installed by knowledgeable consumers familiar with electrical wiring practices who also follow the instructions accompanying the device. When in doubt about the proper procedure, contact a qualified electrician.