X-ray is part of the electromagnetic spectrum, with frequency higher than ultraviolet radiation. The frequency of X-ray covers a wide range. It can go through many solid materials. X-rays can be produced by hitting metal with fast-moving electrons. X-ray photography is used in medicine to see bones and cancer, and other things inside bodies.
X-rays are tiny packets of energy that interact with atoms in the body. The way they interact depends on the power of the x-rays. X-rays with low-level energies go through the Photoelectric effect, mid-level energies go through Compton scattering, and high-level energies go through pair production. Medical x-rays can experience the Photoelectric effect and sometimes Compton scattering. Radiation therapy treatments used to treat cancer use Compton scattering and sometimes Pair production.
There are small amounts of X-rays in the atmosphere. X-rays can change living cells. This means that exposing the human body to high doses of x-rays for a long time should be avoided. Changing living cells can be dangerous. It can cause cancer and other diseases. It can also be good, as cancer cells can be killed that way. Like with any treatment, there are side-effects.