What are the requirements to become a certified pilot?

This is perhaps one of the most important questions you can ask because it defines EXACTLY what is required to be accomplished in order to be eligible for your certificate. The requirements are listed in the Code of Federal Aviation Regulations.

You can start your training at any age, but in order to fly airplanes without an instructor you must be 16 years old. In order to become a Private Pilot of a single engine airplane you must:

Be at least 17 years old
Read, speak, write and understand English
Take a knowledge Test

and, meet the flight time listed below:

40 hours total time in the aircraft
20 hours is with an instructor
10 hours by yourself (solo)

The 20 hours with an instructor will include:

3 hours of cross country flying (50 nautical miles or further)
3 hours of flight training by reference to instruments
10 takeoff and landings at night
1 night cross country flight (totaling more than 100 nautical miles)
3 hours of night training total
3 hours of flight training within 60 days of your flight with the FAA

The 10 hours solo flying will include:

3 take off and landings at an airport with a control tower
5 hours of cross country flying
1 long cross country flight