Radio is the technology of using radio waves to carry information, usually through the transmission of electromagnetic waves from one place to another. The word “radio” can refer to either the electronic device that generates the waves, or to the broadcasted content itself.
Radio waves were first identified and studied by German physicist Heinrich Hertz in 1886. Hertz showed that they could be used to create electrical sparks, and he also found that they could reflect off of objects like metal surfaces. In 1895, Italian inventor Guglielmo Marconi began experimenting with using radio waves to transmit telegraph messages wirelessly. His experiments led him to build the first true radio transmitter and receiver, and he successfully sent a wireless telegraph message across the English Channel in 1897.
The development of practical radio communications began in earnest in the early 1900s. In 1906, Canadian engineer Reginald Fessenden made the first voice broadcast over radio when he read a passage from the Bible on Christmas Eve. The following year, American inventor Lee De Forest patented his three-electrode vacuum tube, which made long-distance broadcasting possible by amplifying weak signals. De Forest’s invention paved the way for such pioneering broadcasters as David Sarnoff (the founder of NBC) and William Paley (the founder of CBS).
In 1920, KDKA in Pittsburgh became the first commercially licensed radio station in America. The popularity of radios exploded in 1922 when more than 500 new stations went on air; by 1923 there were nearly 2 million radios in use in the United States alone. As more and more people tuned into broadcasts, advertisers quickly saw potential in this new medium and began sponsoring programs. This marked the beginning of modern commercial broadcasting as we know it today.
During World War II, radio played an important role in both military operations and civilian life. Military commanders used it to coordinate troops and supplies; meanwhile, civilians relied on news broadcasts for information about what was happening on battlefields around the world. After