X-rays are electromagnetic waves.  They have the ability to penetrate many types of material.  The x-ray machine produces these electromagnetic waves and they pass through your pet's body and then into a special kind of film, exposing the film in the same way that light exposes camera film to create pictures.  Because fat, muscle, bone, air, and tumors all absorb different amounts of the electromagnetic waves, the x-ray film gives the veterinarian an impression of different types of structures within the body.  They can be complex to read, but when used with other diagnostic methods x-rays are a non-invasive and powerful way to get your pet the best health care for his or her health problem.