Amateur radio is a popular technical hobby that uses radio frequencies for exchange of messages, wireless experimentation, self-training, and emergency communications. It is the only hobby governed by international treaty.

Radio amateurs transmit radio signals on a number of designated frequency bands for various purposes:

• Contacting people all over the world
• Competing in international competitions to test good you are as an operator
• Technical experimentation — many of the leaps forward in radio technology have been initiated by radio amateurs
• Communication through amateur satellites or with the International Space Station
• Providing communications at times of emergencies