There are many types of nails. Here are a few of the most common ones and their uses.
1. Round wire nail.
This nail is most commonly used for construction work. This nail will split wood quite easily if used near a knot or close to the end of a piece of wood. One way to avoid the wood splitting is to hit the point with the hammer to blunt it. The nail then punches a hole as it's hammered in instead of parting the wood fibres, putting pressure sideways to the nail causing it to split.
2. Oval wire nail.
This nail is less likely to split wood. As it is hammered in it turns to lie with it's smallest diameter in line with the grain of the wood. This way it doesn't put as much pressure when it parts the wood fibres. However if the two pieces of wood to be joined have the grain at 90 degrees to each other, they are more likely to split the bottom piece of wood than round nails as you are forcing the greater diameter of the nail between the fibres.
3. Lost head nail.
This nail is oval like the one above but the head is shaped so it can countersink itself. Most commonly used for fixing floorboards as the head of the nail disappears below the surface of the wood. The splitting of the piece of wood below is not a problem as the joist is quite thick and unlikely to split.
4. Annular nail.
This nail is most often used in rough construction work such as roof timbers. The annular rings make it very difficult for the nail to be pulled out. It is also used for fixing plywood in place.
5. Panel pin.
These nails come in various lengths and as the lost heads do, they countersink themselves. Most often used for fixing mouldings or thin ply sheeting into place.
When nailing close to the edge or end of a piece of wood, it is advisable to drill a pilot hole of half the diameter of the nail first. This will stop the wood splitting.
When nailing hard wood it is advisable to always drill a pilot hole. Hard wood will split much more easily than a soft wood as the fibres don't compress and move out of the way as easily.
When nailing into the end grain of a piece of wood it's best to do it at an angle. This reduces the possibility of the nail pulling out.