Cinematography is the art of motion-picture photography. Cinematographers use a lens to focus reflected light from objects into a real image that is transferred to some image sensor or light-sensitive material inside a movie camera. Wikipedia
Hallo Herr Kim! The definition is very good! I like the one that says “The cinematographers are the heads of the camera, grip and lighting crew on a set, and for this reason, they are often called directors of photography or DPs.”