Those are not usually used by homeowners, but are common in construction as a generic fastener. They used to be used to attach electric wire, are used to fasten stuff like the tar-paper or waterproof wrap to walls, maybe roofing felt (not the preferred method), sometimes lo-budget stucco guys use those to attach the wire prior to stucco application (also not an approved method). And as a common name applies, they can be used to attach metal wire screening as fencing or on a frame to make chicken coop, pigeon coop, or cage for other types of animals.