In 1920 Vladimir Zworykin invented something which has had a profound impact on almost all the inhabitants of the world since then. What was it?

Russian-American inventor Vladimir Zworykin was a pivotal figure in the transition from mechanical to electronic television. Early attempts at sending images electrically relied on cumbersome mechanical systems with spinning disks, which produced only tiny, flickering, low-resolution pictures. Zworykin, who began his work at Westinghouse in the early 1920s after immigrating to the US, envisioned a system that operated entirely electronically, a breakthrough that would pave the way for television as we know it.

His system was based on two key inventions: the iconoscope and the kinescope. The iconoscope acted as the eye of a camera, converting a visual image into an electronic signal, while the kinescope was the receiver, or picture tube, which turned that signal back into a visible image on a screen. He filed the first patent for his all-electronic system, which used cathode-ray tubes for both the transmitter and receiver, in 1923. Despite a lackluster initial demonstration for his bosses, who famously told him to work on something "a little more useful," Zworykin's persistence ultimately led to the technology that formed the basis for television broadcasting for decades.