Who developed wireless telegraphy?

Wireless telegraphy was developed by Guglielmo Marconi.

He built the first practical radio-telegraph system and sent signals across long distances around 1895 to 1901.

Heinrich Hertz proved the existence of radio waves but did not develop the telegraph system.

Thomas Edison worked on electric light and the phonograph, not wireless telegraphy.

J. C. Maxwell predicted electromagnetic waves in theory, without building the wireless system.

Marconi turned the science of radio waves into working long-distance communication.