The Sport pilot certificate was created in 2004 to meet demand from pilots flying small, low-powered aircraft, and offers limited privileges. It is the only powered aircraft certificate that generally does not require a medical examination; a driver's license can be used as proof of medical competence.

If you are an aviation enthusiast seeking your first pilot certificate, the sport pilot certificate provides the easiest and least costly way to fly for fun and recreation.

The minimum required training time for the different Special Light Sport Aircraft categories are:

Airplane: 20 hours
Powered Parachute: 12 hours
Weight-Shift-Control (Trikes): 20 hours
Glider: 10 hours
Rotorcraft (gyroplane only): 20 hours
Lighter-Than-Air: 20 hours (airship) or 7 hours (balloon)
To earn a sport pilot certificate, one must:

Be at least 16 to become a student sport pilot (14 for glider).
Be at least 17 to test for a sport pilot certificate (16 for gliders).
Be able to read, write, and understand English.
Hold a current and valid U.S. driver’s license as evidence of medical eligibility (provided the FAA didn’t deny, revoke, or suspend your last medical certificate application). Alternatively, you can also use a third class airman’s medical to establish medical fitness.
Pass an FAA sport pilot knowledge test.
Pass a FAA sport pilot practical (flight) test.

Courtesy of EAA (link http://www.eaa.org/learntofly/sportpilot/)