Geometrical optics:

Geometrical optics includes light reflection, refraction and optical elements such as lenses, mirrors, prisms, and fibers.
Reflexion and refraction of light principles are simply derived from experience, but well demonstrated by the Huygens’ method. In Geometrical Optics, the analysis of the behavior of light is carried out with light rays.
The second other main division of Optics is called physical (wave) optics. This field based on wave function concept allow us to understand light wave interference, diffraction, polarization, and thin film coatings.