Hi. Always heard of HAM and HF. I know what HAM is for, but i really have no idea as to what HF is used for.
Near the turn of the century in the early 1900's, radio was shared between those broadcasters backed by government or corporate entities. There were also those that took apart coils and whatnot out of Model T fords or whatever they could cobble together themselves, and used them for their radio equipment - aka amateurs.
Most of the activity was in the longwave and even AM broadcast bands up to about 2 mhz, where both commercial and amateur stations coexisted on the same bands, but eventually interference problems arose without any sort of regulation.
Amateurs were then assigned to the "useless" frequency bands for experimentation above the AM broadcast band, ie about 2Mhz and higher - designated as high-frequency, or HF.
The commercial and government stations didn't really realize the utility of HF with its capability for very long distance communications due to the ionosphere at first. Of course this changed very quickly so now everyone has access to HF, albeit with spectrum regulations to prevent the problem that existed with interference back in the turn of the century.
So amateurs, aka "hams" who are not sponsored by anyone but themselves, still exist, although they can be found across the whole variety of spectrum, not just HF anymore. Most don't have to rip apart coils out of their cars anymore, but the fact is it can still be done!