Plain English Meaning
A check-up with an instructor that every pilot must pass at least once every two years to keep flying as pilot in command. It includes some ground discussion and some flying, and the instructor signs your logbook when you've satisfactorily completed it.
Full Definition
A recurrent proficiency check required by 14 CFR 61.56, consisting of a minimum of one hour of ground training and one hour of flight training conducted by an authorized flight instructor. A pilot must satisfactorily complete a flight review within the preceding 24 calendar months to act as pilot in command of an aircraft.
Context Anchor
You will see this term in pilot currency requirements, rental checkout discussions, logbook endorsements, and .