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Radio is a way to send electromagnetic signals over a long distance, to deliver information from one place to another. A machine that sends radio waves is called a transmitter, while a machine that "picks up" the signals is called a receiver or antenna. A machine that does both jobs is a "transceiver". When radio signals are sent out to many receivers at the same time, it is called a broadcast.
Television also uses radio signals to send pictures and sound.
Airplanes and other things may be used under radio control. Radio signals can be used to lock and unlock the doors in a car from a distance.
Sound can be sent by radio, sometimes through Frequency Modulation (FM) or Amplitude Modulation (AM).[1]