Some of this stuff you might already know, so I hope you don't feel like I'm insulting your intelligence or anything. I think it's cool that you asked about it, and I hope you get a license and join in some day.
Amateur radio is called that because it must be "solely with a personal aim and without direct monetary or other similar reward."* (The word amateur comes from a Latin word, "amador" I think it is, for "lover." Literally, someone who does something just for the love of it.) Ham radio is actually a bunch of hobbies-within-the-hobby. You got guys who like to see how far away they can make contacts while using minimal transmitter power. You got guys collecting "QSL" cards (confirmation of a two-way contact) from all around the world. You got guys doing EME (Earth-Moon-Earth, or "moonbounce"), Amateur Televison, packet radio, and I don't know what-all else.
Didja know Joe Walsh is a ham, and has included brief Morse Code messages in a couple of his songs?
It's a hobby, but the reason hams get all those different bands ("frequencies from DC to light"
) to play with is that they do so much public service stuff. I haven't done anything on 2 meters in ages, but years ago, there were a lot of weekends when a bunch of us would turn out to help one of our ham buddies who was in a local Lions Club or similar service organization, providing communications for checkpoints along the route of a walkathon or some other event. Working non-emergency events like that helps you prepare to do comms during an emergency, too.
One summer afternoon way back when I lived in MA, I heard a guy with a "0" (zero) area callsign (meaning his license was initially issued in the region that includes CO, IA, KS, MN, MI, NE, MO, ND and SD) on the local 2-meter repeater. I heard him key up and say "W0?? [?? being the letters of his Extra class callsign] testing. What repeater is this?" It was a weekday, when pretty much everyone else was at work, so I answered with my callsign and said "You're on the K1KKM repeater in Haverhill, MA. Where are you?" I figured he was just visiting the area, but it turned out he was on the southern end of Campobello Island. (Yeah, the one that's in New Brunswick.) He was running an Icom handheld, into a beam antenna, and Mother Nature was doing the rest of the work.
I rank that exchange right up there with the time I was up in a forest fire tower in NH, and a visitor had come up with his 2M handheld, which he was using to "hit" a repeater somewhere in MA, with a 20M link to a guy in Scotland. If that was before I got my license, it was probably one more thing that pushed me towards becoming a ham.
Good times.
Hope this helps.
*Wikipedia expressed that so much better than I could.