About flat vs smooth shading

Above about flat vs smooth shading

Flat shading is a lighting technique used in 3D computer graphics. It shades each polygon of an object based on the angle between the polygon's surface normal and the direction of the light source, their respective colors and the intensity of the light source. It was used for high speed rendering where more advanced shading techniques were too computationally expensive. But by the end of the 20th century affordable graphics cards were offering smooth shading that were also very fast, making flat shading for speed reasons unnecessary.

The disadvantage of flat shading is that it gives low-polygon models a faceted look. Sometimes this look can be advantageous though, such as in modeling boxy objects. Artists sometimes use flat shading to look at the polygons of a solid model they are creating.