if this isn't clear enough, I don't know what is!!
 

I didn't made this but I guess this image says alot of what's good and what isn't! ;)

'course, when it's games, Triangles are good, too. :)

heh.. I posted this a While back...

-Emo

why are quads better than tris? and if Quads are so much better why dont they make game engines run on quads?

hmmm good question

Quads are better when you're dealing with hi-res models. Quads make better results when smoothed or converted to SubDs. Triangles are to be avoided as much as possible for this reason when making hi-res projects.

In games, though, you DON'T smooth or convert to SubD, and game engines automatically triangulate models. However, it's usually a good idea to triangulate the model yourself in order to make sure the edge flow is as you want it.