X-rays refer to radiation that travels through the air like light or radio signals. X-ray energy is high enough that some radiation passes through objects (such as internal organs, body tissues, and clothing) and onto x-ray detectors (such as film or a detector linked to a computer monitor). In general, more dense objects (such as bones and calcium deposits) absorb more radiation, reducing the amount of radiation that passes through to the detector. Therefore, more dense objects leave an image on the detector (that is, they appear lighter) than less dense objects (which appear darker). This is why bones appear white on x-ray images. Specially trained or experienced physicians (including radiologists) can read these images to diagnose medical conditions or injuries.
A typical medical x-ray, or x-ray radiograph, produces a two-dimensional picture and can help find fractures (broken bones), tumors and foreign objects. Medical x-rays are also used in other types of examinations and procedures, including CT scans, mammography, and interventional fluoroscopy.