Who made the discovery of X-rays?

The story behind the answer

Wilhelm Conrad Roentgen discovered X-rays in 1895 while experimenting with cathode rays. He noticed a nearby screen coated with barium platinocyanide glowed even though it was shielded—evidence of an unknown, penetrating radiation he called “X-rays.” He produced the famous image of his wife’s hand, showing bones and a wedding ring, and received the first Nobel Prize in Physics in 1901.

Remember it this way: X-rays were once called “Roentgen rays,” directly linking the discovery to his name. The other figures didn’t discover X-rays—Einstein explained the photoelectric effect, Edison developed the fluoroscope (an imaging device) after the discovery, and James Watt improved the steam engine. So, X-rays = Roentgen rays = Wilhelm Conrad Roentgen.