The Polygon from The Guerrilla CG Project on Vimeo.

From Guerrilla CG:

The polygon is the basic building block of all 3d models. Here we discover its properties, like the face normal, which shows the direction the polygon is facing and it's three components the face, edge and vertex. Complicated objects are made of lots of polygons put together. (2:26)

*Edit, the terms "Planar" and "Non Planar" should be "Coplanar" and "Non Coplanar" respectively.

GuerrillaCG : The Polygon GuerrillaCG explains the polygon: the basic building block of all 3d models. (2:26) Watch		GuerrillaCG : Multisided Polygons GuerrillaCG explains multisided and intersecting polygons. (3:56) Watch
GuerrillaCG : Objects GuerrillaCG explains objects and why they are useful. (3:52) Watch		GuerrillaCG : Primitives GuerrillaCG explains primitives, and how to use these convenient starting points. (3:24) Watch
GuerrillaCG : Subdivision Artifacts GuerrillaCG explains the relationship between topology and smoothing. (5:29) Watch