Function
According to Ham Universe, shortwave radio signals can be directed all around the world by broadcasters because they bounce from the ionosphere, which functions to propagate signals for long distances. The quality of the signal, however, will vary depending on factors like location and quality of equipment.
Uses
Shortwave radio is used for international broadcasting, local emergency channels and long-distance transmissions to ships or aircraft. Transmissions from world band radio stations like Radio Cuba or Radio Japan can be heard all over the world, and oftentimes these stations will air broadcasts in English. Shortwave radio transmissions are also used by amateur, or ham, operators to listen in and communicate with other shortwave operators.
Equipment
All that is truly needed to hear shortwave broadcasts is a radio capable of receiving these signals and a list of frequencies. Shortwave radios differ by tuning method, size and frequency range, according to Radio Shack. The more time spent finding different channels and exploring various frequencies will help you to understand your shortwave radio's strengths and limitations. An external long-wire antenna is usually necessary to receive distant stations.