The FAA requires pilots to maintain a certain recency of flight experience, in order to maintain proficiency on the aircraft they fly. Firstly, every 90 days you must make at least three takeoffs and landings in the same category, class, and type of airplane (if a type rating is required). You must by the sole manipulator of the flight controls during these takeoffs and landings.
If the airplane to be flown is a tailwheel, then the landings must be performed in a tailwheel airplane (of the same category, class, and type, if required) and the landings must be made to a full stop, as opposed to touch-and-go landings.
If the airplane is to be flown from one hour after sunset to one hour before sunrise (night time), then the landings must have been made during this period and to a full stop.
If pilots do not have the required landings, a flight can be made in order to perform these takeoffs and landings. However, no persons or property can be carried until this 90 day landings recency requirement has been met. All that is required is the pilot perform and log the landings. That pilot has then met the landings recency requirement and may carry passengers and property.
Secondly, pilots have to have a flight review every 24 calendar months to stay legal to fly. A flight review is a one hour ground session and a one hour flight with a flight instructor, with additional training time if the instructor thinks it necessary. The instructor then provides a logbook endorsement for the training and the pilot is good for another 24 months.
A flight review is not required for any pilot who has passed a checkride, performed by a FAA examiner, for a new certificate or rating within the last 24 months.
§ 61.57 Recent flight experience: Pilot in command.
§ 61.56 Flight review.