Amateur radio began almost as soon some of the details of Marconi's successful radio experiments became public. People with no special interest in commercializing radio or pursuing it as a career began trying to use radio communication just for fun. The first amateur radio, like the first commercial radio, used a variant of the Morse telegraph code (called International Code) to transmit messages by turning a radio signal on and off in a rhythmic pattern which spelled out letters, numbers, and a few punctuation marks. In the beginning of amateur radio most amateurs were much more interested in the fact of the communication than in the content. They exchanged information only about their location, name and maybe the weather. They wanted to know how far away the other station was. Others fairly soon tried to give some utility to their hobby by transmitting messages for friends or anyone else who would give a message. A third group, who became known as "ragchewers", simply gossiped and chatted, making friends whom they might never see. Others were experimenters, who tried new ideas or looked for new frontiers.
Until the late 1940's amateur transmitters were on fixed frequencies. There were two methods of making a contact. One was through the call sign CQ, which had originally been adopted by ship to shore and ship to ship radio as the indication that the station was calling any station which wished to answer. After calling CQ the operator tuned the receiver over as much of the amateur band he/she was operating on as was convenient, hoping that someone was responding by transmitting her/his callsign back. Conversely the operator would listen for someone calling CQ, and hope that his answer would be heard. The other means was by prearrangement, on schedule.
Until fairly recently the number in the callsign of U.S. amateur stations indicated the area in which the licensee resided. As a result, when I moved to Philadelphia from Columbus my callsign was changed, initially to W3LXS and then because of a special situation to W3UKI. When I planned to return to the Columbus area and was concerned about the new callsign I might be given, I took another special opportunity to change to W3EL, and when I came back to Ohio I received K8EF, which I now hold.
Amateurs played a very important part in the development of VHF and UHF radio, using wavelengths even shorter than the "short waves". Transmission on these wavelengths seemed, in the 1930's, to be limited to very short ranges, so they were of little interest to commercial radio at that time. A few amateurs (who quite proudly accept the slang designation "ham", a word of much disputed origin), just interested in experimentation, found that these wavelengths had a much more complicated pattern of propagation than was initially assumed. When commercial development of FM and television broadcasting, local (particularly emergency, police and fire for instance) communication and "microwave" relaying of telephone and television signals began, the information developed by amateurs about the properties of these wavelengths became very important.