Arc fault (AFCI) protects against two types of wiring faults so your house doesn't burn down. One is when wires become loose in a connection and the electricity arcs in the connection and creates heat. The other case occurs most often when somebody puts a nail through a hidden wire in the wall and it doesn't short but an arc starts and over time it creates heat and may cause a fire. For the most part, right now there are only AFCI breakers. AFCI receptacles are on their way, but using them requires all of the wires between them and the panel be in metal conduit. There are also AFCI breakers which are a combination AFCI and GFCI.
Depending on which US state you live in, the national electric code currently enforced has varying requirements for AFCI. But it is fact that over time, the code is going to pretty much require either GFCI or AFCI at most receptacles in a house depending on the location. For instance, bedrooms, kitchens, bathrooms, basements, garages all require GFCI and nearly everywhere else is going to require AFCI (in time).
Depending on which US state you live in, the national electric code currently enforced has varying requirements for AFCI. But it is fact that over time, the code is going to pretty much require either GFCI or AFCI at most receptacles in a house depending on the location. For instance, bedrooms, kitchens, bathrooms, basements, garages all require GFCI and nearly everywhere else is going to require AFCI (in time).