Amateur Radio, commonly called 'ham radio', is a hobby enjoyed by many people throughout the world.
It is the study of electronics, radio waves, and most of all, it's fun.
Within amateur radio, one can pursue fascinating topics such
as antenna theory, satellite communication,
DX communication over thousands of miles using the
ionosphere to refract radio waves, and
low-power or QRP operation.
See also Morse code, electromagnetism, and Electromagnetic radiation.
Also: lists of Country_codes, especially the ITU_Prefix that is used for Callsigns.
For more information, please see http://www.arrl.org
With the advent of the internet (offering email, music, broadcast audio, video, voice over IP VoIP) the popularity of ham radio is diminishing somewhat in advanced countries.