I've always found these images [1,2] from Wikipedia to be helpful in explaining how the torus is a product of two circles. [1] http://en.wikipedia.org/wiki/Tor

I've always found these images [1,2] from Wikipedia to be helpful in explaining how the torus is a product of two circles. [1] http://en.wikipedia.org/wiki/Torus#mediaviewer/File:Sphere-like_degenerate_torus.gif http://en.wikipedia.org/wiki/Torus#mediaviewer/File:Sphere-l... [2] http://en.wikipedia.org/wiki/Torus#mediaviewer/File:Torus_cycles.svg http://en.wikipedia.org/wiki/Torus#mediaviewer/File:Torus_cy...