A nail’s a pretty basic bit of hardware, right. Have a look, and you’ll see there’s a little more to it.
Head: For thinner, weaker materials, like roofing felt or shingles, oversize heads help reduce the chance of the head ripping through the material. For finishing work, small heads are better, and countersunk heads give purchase for a nail punch. Of course, the smaller the head, the easier it pulls through the wood.
Shank: The most common shank styles are plain and threaded (either like a screw or with individual rings). If you want the nail to hold well (withdrawl resistance) — even under changing moisture conditions — threaded is best. The ring-shank is tougher to withdraw than the screw-shank, but once it pulls out a bit, it rips the wood that held it and loses its resistance. The screw-shank, like its namesake, screws out, leaving the wood that binds it in place. They’re also thicker at the threaded portion of the shank, so they’re stronger.
Tip: A long, sharp point drives easily, but wedges the wood apart and can split the wood. A blunt or non-existent point punches out the wood, reducing splitting, but is tougher to drive. A blunted, diamond-shaped tip is a happy medium. But near the end of a board, drill pilot holes or blunt the nail further by tapping it against a hard surface.
Material: Most nails are low-carbon steel. Carbon-hardened steel gives you concrete nails, which can be good for dense woods, too. For outside use, where water, wood preservatives, and naturally corrosive woods will rust steel, use hot-dipped galvanized steel, which has more zinc coating than electrically galvanized. Stainless steel lasts even longer, but costs more.