What is an x-ray?
Radiography, or as it is most commonly known, an x-ray, is the oldest and most frequently used form of diagnostic medical imaging. Conventional x-ray images are produced when radiation is passed through the body part of interest, exposing photographic film. The image on the film is produced as a result of differential absorption of x-rays by different body tissues. The films are taken by a radiographer (technologist trained in medical imaging) and interpreted later by a radiologist (a specialist doctor trained to read medical images). Bone and some organs (such as lungs) especially lend themselves to this form of diagnostic imaging. Common exams performed include chest x-rays and x-rays of the bones of the limbs and spine.
More info
Types of x-ray - from www.radiologyinfo.org