It is hard to imagine what the modern world would look like without the constant exchange of a huge quantity of information. It is currently disseminated by various means such as newspapers, telephone and the Internet. However the fastest way, and sometimes the only way, is by radio. This is where the transfer is by electromagnetic waves, traveling at the speed of light. In radio communication, a radio transmitter comprises one side of the link and a radio receiver on the other. No conductor of any kind is needed between them, and that's how the expression Wireless Link came into being. In the early days of radio engineering the terms Wireless Telegraph and Wireless Telephone were also used, but were quickly replaced with Radio Communication, or just Radio.