A type rating is a regulating agency's certification of an airplane pilot to fly a certain aircraft type that requires additional training beyond the scope of the initial license and aircraft class training. What aircraft require a type rating is decided by the local aviation authority. In many countries pilots of single-engined aircraft under a certain maximum weight (5,700 kg or 12,500 lb, typically) do not require a type rating for each model, all or most such aircraft being covered by one class rating instead. There are exceptions to this, e.g. under the European Joint Aviation Authorities (JAA) regulations the piston version of the Piper Malibu does require its own type rating. In New Zealand and South Africa there is no class rating, each aircraft model requires its own rating. Countries which have adopted the class rating system for small aircraft typically require additional training and license endorsement for complexity features such as conventional undercarriage (tailwheels), variable-pitch propellers, retractable undercarriage, etc.
Starting in 2006, the Federal Aviation Administration (FAA) in the United States requires co-pilots (second-in-command, or SIC) to have a 'SIC Type Rating' for aircraft requiring a crew of two, and otherwise requires a type rating to act as pilot-in-command (PIC) to fly internationally, or over international airspace. This is in order to remain compliant with the International Civil Aviation Organization (ICAO). This is outlined in Code of Federal Regulations Title 14 §61.55 (14 CFR 61.55). Such a type rating is not required for operations completely within the United States. Obtaining a SIC Type Ratings is significantly less rigorous than obtaining a 'full' or Pilot in command (PIC) type rating.
An instrument rating is required for some type ratings.
In the United States some type ratings can be issued with a "visual flight rules (VFR) only" limitation when the type rating checkride was conducted without instrument flight rules (IFR) approaches or operations, but only VFR maneuvers and procedures. This is most typical in older aircraft (i.e. Ford Trimotor, N-B25, B17, etc.)
Many commercial aircraft share type ratings, allowing qualified pilots to operate both of them with minimal transition training. Examples include the Boeing 757 and Boeing 767, Boeing 777 and Boeing 787, Airbus A330 and Airbus A340, and all of the members of the A320 family (the A318, A319, A320, and A321).