Short answers, pulled from the story.
Heinrich Hertz first proved the existence of radio waves on the 11th of November 1886. He generated and detected these waves in a laboratory setting, confirming they traveled at the speed of light. His spark-gap transmitter experiments laid the groundwork for future communication technology.
Guglielmo Marconi achieved the first transatlantic radio transmission on the 12th of December 1901. He sent a signal from Cornwall to Newfoundland, proving radio waves could follow the curvature of the Earth. This feat earned him the 1909 Nobel Prize in Physics shared with Karl Ferdinand Braun.
The first commercial radio broadcast occurred on the 2nd of November 1920. Westinghouse Electric and Manufacturing Company in Pittsburgh aired the results of the United States presidential election under the call sign KDKA. This event marked the birth of the broadcasting era.
The word radio derives from the Latin word radius meaning spoke of a wheel or beam of light. The British Post Office officially adopted the word radio in instructions issued on the 30th of December 1904. This decision was universally adopted by the 1906 Berlin Radiotelegraphic Convention.
Radio waves have long wavelengths that allow them to pass through the atmosphere and most building materials without being absorbed. Unlike X-rays or gamma rays, radio waves can bend around obstructions through diffraction and tend to be scattered rather than absorbed. This unique ability allows signals to reach receivers even when they are not in direct line of sight with the transmitter.
The International Telecommunication Union divides the radio spectrum into 12 bands ranging from extremely low frequency to extremely high frequency. The ITU allocates these bands to prevent interference and ensure that two transmitters in the same area do not jam each other's signals. Governments license transmitters and assign unique call signs to broadcasting stations while regulating unlicensed devices under specific rules.