@Felthry Oh, okay I thought you were just throwing shader. :-P
(For serious though, a 'shader' is just a set of code that tells a 3D rendering engine how to display the pixels, I believe. It involves how the lighting works, what sort of fade-into-atmosphere effects happen, even how the geometry of the world is displayed (such as fisheye lens-style, field of vision, or even perceptual curvature of the plane around you.) )