This category is common nearly for all European countries. It has different abbrevations, as UL, ULL, ULM. In Italy for instance, it is called microlight aircraft. Aircraft in the UL category often can be registred also as light sport aircraft in USA.
Typical dual seater UL airplane has an empty weight +-280 kg and is powered with a +-80 hp engine.
Basic definitions of an ultralight aircraft in EU
MTOW: 300 kg (single seater), 450 kg (dual seater), 472.5 (dual seater equipped with BRS - balistic recovery system)
Stall speed: 65 km/h in landing configurations (flaps etc. are allowed)