Every two years a pilot must receive ground and flight training with a qualified instructor.
The flight review consists of at least one hour of ground instruction and one hour of flight time with a qualified instructor. The review should cover applicable regulations and flight operations typical of the type of flying conducted. The purpose of the flight review is to ensure that pilots are reasonably proficient to conduct safe flight. Should the flight instructor believes additional training is warranted, a failure is not logged. There are some exceptions to the flight review and these include current students with a solo endorsement, a pilot who has accomplished a flight proficiency award program, a pilot who passed a practical test for a pilot certificate, rating or operational privilege, or the renewal of a flight instructor certificate.
14 CFR 61.56 Flight review