>>522301>Some engines are being able to display quads.
Nope, maybe they can handle quads, but no display them, the draw type flag in both opengl and directx for passing quads is deprecated and I don't think works.>A polygon has 3 sides.
Wrong, it has 3 or more sides/edges. A quad is still a polygon and it exists in real life geometry as well as geometry, it even exists in computer graphics.>A Quad is 2 polygons sharing an edge.
Wrong, a quad is a polygon with 4sides/edges.>An Ngon is a polygon with more than 5 points and no edges connecting them.
Wrong, an ngon is a term used in 3dcg mainly, which stands for a polygon with more than 4 sides, so a polygon with 5 sides, also known as a pentagon is an ngon, so is a hexagon and so on.>Engines automatically triangulate Quas and Ngons because that's how it reads them.
Correct(although not all engines do it, most need the model triangulated, in order to read it properly).>When Doing hardsurface modeling its best to stay with Quads and occasional Ngons if the face is completely planar
Debatable, usually whatever modelling you're doing, the best option is to stay in quads, except if its faux poly, which favors flat shaded triangles, pic related.
Please don't post false information anymore, it's confusing to the newbs.
If you're interested in understanding 3d graphics, read up on opengl, direct x, or topology.