X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays.X-rays with photon energies above 5–10 keV are called hard X-rays, while those with lower energy are called soft X-rays.Due to their penetrating ability, hard X-rays are widely used to image the inside of objects,like in medical radiography and airport security. Soft X-rays are easily absorbed in air.