An amateur radio license is what allows you to get on the air and talk to other hams. Your amateur license allows you to control an amateur station's transmissions.
With a US amateur license, you are allowed to operate wherever the amateur service is regulated by the FCC. This means that wherever you go in the U.S. or it's possessions, you are allowed to operate your amateur station.
When you pass the necessary exams and earn your first license, your application for a new license is passed on to the FCC. Then the FCC grants you an amateur operator/primary station license. You are not legally able to operate until the FCC has granted you this license.
Before you are allowed to operate an amateur radio station the FCC database must show that you have been granted an amateur license. This makes it easier to get on the air faster because you can call the FCC to find out your new callsign shortly after passing your exams (1-2 weeks). After you know what you callsign is, you can get on the air. (Before, you had to wait 6-8 weeks (or longer) for your license to arrive in the mail before you could get on the air.)
There are other ways to get on the air in the U.S.
An amateur service license from the United Nations Secretary of Communications does NOT allow a person to control a U.S. amateur station.
The FCC's full name for an amateur station license is "amateur operator/primary station license". This is because there is a dual nature to a U.S. amateur radio license. The first applies to the operator. The second applies to the station. This can best be analogized to driving a vehicle.
All drivers must have a driver's license. There are various classes of driver's licenses - some allow you to only drive cars, vans, and pick-up trucks. Others allow you to drive commercial vehicles (e.g. buses, semi-trucks). Ham radio operators have different kinds of licenses also - some let them use VHF/UHF frequencies only; others allow them to operate on HF frequencies also.
Your amateur operator license allows you to be a control operator of an amateur radio station. A control operator is any licensed operator who is responsible for the station's transmissions.
There are currently six US amateur operator license classes...
There are four privileges that change from license class to license class
The one thing that does not change with your license class is the authority to send third-party messages (more on this in a later lesson about operating)
Also, each vehicle that is driven on public roads must have a license plate. This identifies the vehicle. In the same fashion, each radio station must have a callsign - this identifies the station's transmissions.
An amateur station is a station in the Amateur Radio service used for radiocommunicaitons. This means that it is not used for broadcasting or for commercial radiocommunications (i.e. business radios). It is used solely for amateur radio use.
Unlike driving a vehicle where you can only drive one car at a time, you may simultaneously control several amateur service transmitters at one time. In fact, there is no limit to the number of transmitters you may control at the same time.
Lesson 7 - U.S. Amateur Licenses
Daniel Reynolds - AA0NI - August 21, 1998