A private pilot licence (PPL) or private pilot certificate is a type of pilot licence that allows the holder to act as pilot in command of an aircraft privately (not for remuneration). The basic licence requirements are determined by the International Civil Aviation Organization (ICAO), but implementation varies from country to country. According to ICAO, an applicant must be at least 17 years old, demonstrate appropriate knowledge and skill, and hold at least a Class 3 medical certificate.[1] Different PPLs are available for different categories of aircraft, such as aeroplane, helicopter, airship, etc.,[1] and are not interchangeable, although experience from a PPL in one category may be credited towards the issue of another.