X-Ray – A form of electromagnetic radiation, just like visible light. It has a specific wave length that is basically used for diagnostic purposes. In a health care setting, x-rays are given off by a machine as individual particles that pass through the body and then get identified by a sensitive film. Dense structures like bone block most of the particles and appear white on the film, structures that contain air are black on the film, and muscle, fat and fluid have different shades of gray.
The science behind basic x-ray is the basis for such radiographs of the body as mammograms, and cat scans (computed tomography or CT scans).
They are a form of ionizing radiation and therefore can be dangerous. However, many standards are used in doing x-rays in order to prevent or greatly limit the possibility of danger.