How do we know x-rays exist?

X-rays are a part of the electromagnetic spectrum, a form of ionizing radiation having high energy, short wavelengths, and extraordinarily high frequencies (30 quadrillion to 30 quintillion Hz). X-rays are divided into two bands, HX (hard x-rays) and SX (soft x-rays).

Like all electromagnetic radiation other than visible light, x-rays are detected by their effects, and by using detectors or phosphor screens (e.g. fluoroscopes).