Arvid Schneider talking a bit about N-Sided or multi-sided polygons that have more than 4 edges. Arvid shows that you can search for N-Sides in Maya by using selection constraints to easily search out, find and highlight the offending polygons.
…With this video I want to show you how to remove n-sided polygons, ngons from your meshes…
Arvid also shows some techniques for dealing with N-sides in Maya by manually adding edges to re-configure how the N-Sides are affected, or by using the Cleanup Dialog for automatically changing N-side configurations.
Arvid notes that “In some occasions especially in real-time engines ngons are so to speak the devil. In a very detailed mesh its hard to see ngons and remove them, therefore I want to show you a really neat selection trick to select specific faces, like ngons, quads, triangles and much more.”