Student
Can solo with instructor's permission; valid for 24 months.
Private
Passengers; day or night VFR; share expenses; valid indefinitely.
For more information, click here
Instrument
May file instrument flight plan; valid indefinitely but recency req'd.
For more information, click here
Commercial
May receive compensation as a pilot; valid indefinitely.
Instructor
May give ground and flight instruction in accordance with FAA regulations; valid 24 months.
Airline Transport
Valid indefinitely.