X-rays are part of the Electromagnetic spectrum. They are a penetrating form of electromagnetic radiation and consist of quantum's of energy (Photon). X-rays are commonly produced by the excitation of atomic Electrons, by firing electrons between a high potential difference towards a target (which is the principle of an x-ray machine).

The target electrons are excited, and as they de-excite x-ray photons are produced. X-rays can also be produced as a result of Bremsstrahlung or by nuclear reactions. X-rays have many uses including medical imaging and industrial quality assurance.