A suggested first step is to visit a nearby smaller airport and inquire about a "Discovery Flight" or "Introductory Flight".
Most flight schools offer these which will include a brief first lesson with a Certificated Flight Instructor ("CFI") where you will sit in the pilot's seat and get to handle the flight controls - typically when 1,000' or more above the ground.
This will introduce you to flying with no commitment. If there is more than one flight school near you, you will want to visit each of them to get a good idea of how they conduct business and decide if they meet your expectations. Some schools are better, friendlier or more modern than others and you can determine if a slightly more expensive school may or may not be worth it.
Student Pilot Certificate and Third Class Medical Certificate (Required to 'solo', or fly by yourself)
Previously this was issued as a combined "Student Pilot Certificate / Third Class Medical Certificate" by an Aviation Medical Examiner.
But now, the Student Certificate is a separate document issued by the FAA. Your CFI will help you get this, but it isn't required until you are ready to solo.
The Third Class Medical Certificate is issued by an Aviation Medical Examiner. Like the Student Pilot Certificate, this isn't required until you are ready to solo.
This is a fairly simple medical exam. The medical is valid for 5 years / 60 months if obtained when under 40 years old, 24 months if issued when 40 or older. See the "Basic Med" information and links under Private Pilot below.
Flight instruction can be received at any age, but to solo an airplane, you must be 16 years old.
Gliders and balloons can be soloed at age 14.
The Student Pilot's logbook is signed by a Certificated Flight Instructor ("CFI") to allow you to solo, and later, to take solo cross-country flights.
No minimum hours are specified, but details of training required are spelled out in Federal Aviation Regulations ("FARs") 61.81 thru 61.95. Most pilots can solo in about 10 hours, but this is widely variable.
Passengers may NEVER be carried by a Student Pilot.
See FAR Parts 61.81-61.95 (Subpart C) for full information
Sport Pilot
The Sport Pilot can fly Light Sport Aircraft ("LSAs") which are aircraft with a maximum weight of 1,320 lbs.
Limited to Day, VFR (Visual Flight Rules / "good weather"), only one passenger and several other limitations (see FAR 61.315)
FAR Part 61 Minimum flight experience (full list is in FAR 61.313)
20 hours total flight time
15 hours dual instruction ('dual' is flight time with an instructor)
5 hours solo, including one 75 nautical mile cross-country solo flight.
A very significant plus is that a Sport Pilot does not need an FAA Medical certificate - only a Driver's License for medical requirements.
See FAR Parts 61.301-61.327 (Subpart J) for full information
Recreational Pilot
The Recreational Pilot is a very restricted certificate and very few pilots pursue this. It existed long before the Sport Pilot became an option.
See FAR Parts 61.96-61.101 (Subpart D) for full information
Private Pilot
The Private Pilot certificate is usually what is referred to when discussing getting a "pilot's license".
Minimum age - 17
Allows carrying of passengers in relatively good weather - Visual Flight Rules ("VFR") both day and night.
Third Class medical required. (Same duration as for Student Pilots listed above). As of May 1, 2017: Recent changes to the regulations allow many operations under "Basic Med". More detail here.
Specified flight training, solo and solo cross-country experience, a "Knowledge Test" and written recommendation from a CFI is required prior to taking the Practical Test (an Oral and Flight Test) from a Designated Pilot Examiner.
Either of two possible sets of rules can be used to get your Private Pilot's License: either FAR Part 141 - at an "FAA Approved" Flight school, or FAR Part 61
FAR Part 61 Minimum flight experience (full list is in FAR 61.109)
40 hours total flight time
20 hours dual instruction ('dual' is flight time with an instructor)
3 hours night, including 10 night takeoffs and landings and a 100 nautical mile night flight.
10 hours solo, of which 5 hours is solo cross-country, including one 150 nautical mile cross-country solo flight.
FAR Part 141 allows some ground simulator time to be applied toward the certificate and has different requirements.
See FAR Parts 61.102-61.117 (Subpart E) for full information
Commercial Pilot
Minimum age: 18
Allows you to earn money for flying.
A Second Class Medical is required. The medical is valid for 12 months for commercial pilot purposes.
Minimum hours under FAR 61.129 : 250 hours.
FAR 141 generally requires fewer hours.
Another Knowledge Test and Practical Test is required.
See FAR Parts 61.121-61.133 (Subpart F) for full information
Instrument Rating
Allows flying in weather 'less-than VFR' or in 'Instrument conditions', such as in the clouds.
Rating goes onto a Private or Commercial certificate.
Minimum hours under FAR 61.65:
50 hours cross-country time as Pilot in Command.
40 hours of simulated instrument time under the 'hood' - which is flying with an instructor while you wear a 'view-limiting device' allowing you to only see the instruments.
FAR 141 generally requires fewer hours.
Another Knowledge Test and Practical Test is required.
See FAR Part 61.65 for full information
Multi-engine Rating
Rating goes onto a Private, Commercial or ATP certificate.
Allows flying multi-engine airplanes.
No Knowledge Test, but a Practical Test is required.
Certificated Flight Instructor
Commercial Certificate and Instrument Rating (or ATP) required first.
Allows you to teach flying - which many people do to build flying experience.
Ratings on the CFI include: Single-Engine, Multi-Engine and Instrument.
An extensive Knowledge Test and Practical Test is required.
See FAR Parts 61.181-61.199 (Subpart H) for full information
Airline Transport Pilot
Minimum of 1,500 flight hours.
There are provisions for an ATP with restricted privileges with 1,000 hours if a Bachelor's degree graduate from certain universities. (See FAR 61.160)
Required certificate to be a Captain for an airline.
A First Class Medical is required. The medical is valid for 12 months if obtained when under 40 years old, 6 months if issued when 40 or older
(for ATP privileges).
Another Knowledge Test and Practical Test is required.
See FAR Parts 61.151-61.169 (Subpart G) for full information