Radio is, by definition, the use of waves to transmit sound and has historically been used as the primary method of broadcasting information, that it at least, until the dawn of the television. However, even today, the radio remains a popular use of entertainment technology.
Radio works by transmitting waves to an electrical conductor which can then decode the information and turn it back into the pattern in which it was recorded. Radio requires an antenna and a transmitter to turn the electrical currents into radio waves and decode them at the other end. Radio transmissions use frequencies between 3 kHz to 300 GHz, however, most commercial stations use only a tiny fraction of this and while remains could technically be broadcast on, it is either dead radio space or sometimes used for other purposes. Other uses of the frequencies include maritime operations, mobile communications, and meteorological operations.
It was in 1864 when James Clerk Maxwell first demonstrated that electromagnetic waves could travel freely through space and in theory proved that radio communications were possible. However, it was some years later in 1894 when Guglielmo Marconi began to explore the notion that waves could be used for transmitting telegraphs and his ideas developed into a full-blown method of communications over the next few years.
Numerous individuals and organizations attempted to transmit sound between 1900 and 1906 but most of their work was unsuccessful. It was the need for communications during World War I that greatly sped up the development of these technologies and by the end of the War, radio was becoming commonplace. By the time of the second world war, radio technologies were so advanced that radio was not only being used as a method of communications but also as a form of entertainment for the masses.
There are two ways in which radio waves can be broadcast and will be familiar to most people. These are commonly known as AM and FM. Amplitude Modulation, or AM, is modulated in amplitude and was the first way of transmitting radio waved while Frequency Modulation, or FM, is modulated in frequency. FM is the preferred choice for commercial radio today as it is less likely to experience interruptions though it can be stopped by physical barriers.