If you're a contractor, the charts and usage tips here will be old hat to you. For the rest of us, this chart helps make knowing which nail or screw to use less of a hit-or-miss prospect.
Unless you're 12 and building a tree fort from stuff you scrounged from the back of your dad's workshop, you've really got no excuse for using the any-nail-will-do philosophy. Nails and screws are constructed in a variety of thicknesses, strengths, lengths and with varying threading and scoring to grip in the materials they were intended for.
The National Retail Hardware Association's guide covers different nail and screw types, how to identify them, and more importantly how to use them to make your project safe and good looking.
Even if you're already familiar with fastener types, their guide is packed with clever tips and tricks like how to use wood grain to conceal nail heads, and how to use a dowel to keep screws from splitting the end of a board. Check out the full guide at the link below for dozens of tips.
Selecting & Using: Screws and Nails [National Retail Hardware Association]