Amateur (Ham) radio
How did this whole thing get started?
This is maybe the oldest "high-tech" hobby in the world,
dating from around the time of World War I. Actually this was merely the
time at which it was recognized, and organized as a hobby. In truth, experimenters,
and hobbyists had been playing around with radio equipment long before
being licensed to do so by the government. Most, if not all of the pioneers,
and inventors of radio had been what we today would call "amateurs", though
this term would hardly do them justice.