X-rays are used to take radiographs in a variety of health care settings.  A radiograph is similar to a photograph, except the image is formed with x-rays rather than light rays on some sort of x-ray sensing media, such as x-ray sensitive film or a digital sensor.  The image is formed when a beam of x-rays is shot through a body.  More dense substances, such as metal or bones, absorb the x-rays creating an absence of x-rays on the x-ray sensitive media where the image forms.  These areas appear lighter in the radiograph than areas where fewer x-rays are absorbed, such as soft tissue or air.   Radiographs are commonly used to visualize bones and teeth as well as masses of denser tissue, such as tumors.