How do the X-rays work?

An X-ray is taken when one develops a fracture of bones. The X-rays can penetrate into the skin, flesh and fats and muscles. But since bones are made of calcium, these rays are absorbed. As a result, the bones get highlighted in the film as shadows. It is why an X-ray of affected portion is suggested to locate the fracture or dislocation of the bones. However, overexposure to X-ray is dangerous and therefore only trained and experienced technicians are employed to carry out X-ray.