For some guys, even wearing a suit can be tricky. For others, it's knowing how to best plop down that initial $300-500 just to get started. But for every man? You have to know what you're looking at before you even begin to make the right choice. Primer, with the help of 7 Regent Lane, offers a seriously helpful, in-depth look at, well, all things suit. They diagram everything from lapels and buttons to sleeves, pockets, and pants.
It's quite well done, and very, very helpful. See it at Primer: A Visual Guide for Understanding Common Suit Features.