Since early in the twentieth century there has been a community of experimenters, and enthusiasts of the art, and skill of radio. This community, given the nature of radio, and the technologies which support it, rapidly grew world wide. Along with technical issues, organizational issues drove the community to organize itself. Naturally enough the organizational effort grew along national boundary's but also a world wide organization was created. In the USA the national organization is called the Amateur Radio Relay League or ARRL.
The ARRL was formed shortly after the US congress passed into law the Radio Act of 1912. There is a brief synopsis of amateur radio here on the ARRL web site.
Radio was once a primary means of mass communication, and most people were introduced to it via the ubiquitous "transistor radio" of the 60's and 70's. But it also allowed for the development of television. Both forms of media outlet use radio or rather electromagnetic radiation. Television uses one particular area of the electromagnetic or radio spectrum. FM radios in vehicles use another. Nowadays computers using "WiFi" use yet another area of the radio spectrum.
Although the radio spectrum is vast, covering tens of hertz (cycles per second ) up to infrared radiation (300 GHz...405 THz), there are practical limitations to how it can be used. Some limitations arise due to technology, others are simply due to the nature of electromagnetic radiation, and where it is used.
Much of the useful regions of the radio spectrum are allotted to commercial or governmental interests. The ranges of radio spectrum are called bands. Small sections of the spectrum have been either allotted to or are shared with amateur users. These allocations of radio spectrum are often referred to as the amateur bands.
For many years I worked for a research unit called LASST at the University of Maine. In 1997, with some prodding by a colleague, I got my amateur radio license. Although I had known about amateur radio since I was a kid, it wasn't until I was in my mid thirties that I did anything about it.
I had a brush with amateur radio as an undergrad at U. Maine in the early 1980's. I met a non traditional student who, among other things, had a stint repairing televisions. He had his amateur radio "ticket". At the time the licensing structure of the amateur service, regulated by the FCC, was quite a bit different than it is today. To get started in amateur radio then, one had to learn the International Morse code (Morse code - wikipedia, Morse code-ARRL, FISTS). There is a good treatise on Morse code by N0HFF available here. It is part history, and part tutorial.
In the 70's and 80's an entry level amateur radio license required, among other things, Morse code copying proficiency of 5 WPM (Words Per Minute) minimum. While I was interested in the hardware of radio, I never got myself to work with the code enough to pass a 5 WPM FCC test. I was also goofing off too much as an undergrad to focus on anything, so amateur radio once again got put on the back burner until 1997.
An entry level amateur radio license in 1997 no longer required 5 WPM Morse code proficiency, so that finally got the door opened for me. Once licensed, my colleague - who knows everyone at U. Maine - and I asked around about the University of Maine Amateur Radio Club (UMARC).
We found the University of Maine Amateur Radio Club's 2m duplexer stuffed into a corner of a departed faculty member's office/lab. Also in our travels we discovered a Dentron MLA-2500 HF (High Frequency) band power amp, collecting dust on the shelf of the EE department's equipment room.
We attempted a bit of a rebuild of the duplexer, and tuned it up, although it remained a bit unstable. It needed another rebuild a few years later by some other dedicated UMARC members.
In the US, the amateur bands span several of the standard band classifications:
There are many satellites which support amateur radio activities. Such satellites are called OSCAR satellites.
On again, off again, restoration of a Hallicrafters SX-42 is covered here.
My ongoing work on a 2m J-pole is here.
The Dentron MLA-2500 RF power amp blew out one of its RFC's (Radio Frequency Choke). That repair is covered here.
The HF rig that feeds the Dentron MLA-2500 is a Ten-Tec Inc. Corsair 560 which also needed some TLC.
Rigs (radios) I use, from time to time...