DX - origin with Morse Code radio operators, means “distance” Possibly in the infancy of radio the term “DX” was coined, so “DX” is around 100 years old.

For Ham (Amateur) Radio operators, CB’ers with their linear amplifiers and Short/Medium Wave listeners (we call Medium Wave “AM” in North America, which is the modulation method, not necessarily bound to wavelength, there is “AM” on the aircraft VHF band which is higher in frequencies than what we know as FM)

The challenge for radio hobbyists enjoy is to listen to, or in the case of Hams/CB’ers is to talk to people hundreds, and often thousands of miles away via radio.