In 2004, the FAA introduced the "Light-sport aircraft" category, which resembles some other countries microlight categories. Ultralight aviation is represented by the United States Ultralight Association (USUA), which acts as the US aeroclub representative to the Fédération Aéronautique Internationale. Types
There are several categories of aircraft which qualify as ultralights in some countries:

Fixed-wing aircraft: traditional airplane-style designs. Weight-shift control trike: use a hang glider-style wing, below which is suspended a three-wheeled carriage which carries the engine and aviators. These aircraft are controlled by pushing against a horizontal control bar in roughly the same way as a hang glider pilot flies. Powered parachute: fuselage-mounted engines with parafoil wings, which are wheeled aircraft. Powered paraglider: backpack engines with parafoil wings, which are foot-launched. Powered hang glider: motorized foot-launched hang glider harness. Autogyro: rotary wing with fuselage-mounted engine, a gyrocopter is different from a helicopter in that the rotating wing is not powered, the engine provides forward thrust and the airflow through the rotary blades causes them to autorotate or "spin up" thereby creating lift. Helicopter: there are a number of single-seat and two-place helicopters which fall under the microlight categories in countries such as New Zealand. However, few helicopter designs fall within the more restrictive ultralight category defined in the United States of America. Hot air balloon: there are numerous ultralight hot air balloons in the US, and several more have been built and flown in France and Australia in recent years.
Definitions
Australia
In Australia, ultralight aircraft and their pilots can either be registered with the Hang Gliding Federation of Australia (HGFA) or Recreational Aviation Australia (RA Aus). In all cases, except for privately built single seat ultralight aeroplanes, microlight aircraft or trikes are regulated by the Civil Aviation Regulations. Canada
United Kingdom
Pilots of a powered, fixed wing aircraft or paramotors do not need a licence, provided its weight with a full fuel tank is not more than 75 kg (165 lb), but they must obey the rules of the air.For heavier microlights the current UK regulations are similar to the European ones, but helicopters and gyroplanes are not included.Other than the very earliest aircraft, all two-seat UK microlights (and until 2007 all single-seaters) have been required to meet an airworthiness standard; BCAR Section S.
In 2007, Single Seat DeRegulated (SSDR), a sub-category of single seat aircraft was introduced, allowing owners more freedom for modification and experiments. By 2017 the airworthiness of all single seat microlights became solely the responsibility of the user, but pilots must hold a microlight licence; currently NPPL(M) (National Private Pilots Licence). New Zealand
Ultralights in New Zealand are subject to NZCAA General Aviation regulations with microlight specific variations as described in Part 103 and AC103-1. United States
The United States FAAs definition of an ultralight is significantly different from that in most other countries and can lead to some confusion when discussing the topic. The governing regulation in the United States is FAR 103 Ultralight Vehicles.