Who was responsible for the development of the first practical radio?

Guglielmo Marconi, an Italian inventor, brought electromagnetic waves out of the laboratory and into the world. He began with short-distance broadcasts in his own backyard. In September 1899, he astounded the world by telegraphing the results of the America's Cup yacht races from a ship at sea to a land-based station in New York. By the end of 1901, Marconi had founded his own commercial wireless company and broadcasted the first transatlantic signal.

Source: PBS