Fasteners, like screws, come with a variety of different head drive shapes. The ones that I want you to be able to identify are; straight/flat, Phillips, square, Allen, Torx, and hex head.
Straight or Flat head – Used to be used a lot in wood working way back but now are used mostly in electrical (wire terminals, face plate covers, etc). When using this type of driver head be sure to use the correct size; if not then you will either strip out the head or the driver. A straight head looks like a minus sign.
Phillips head – This is the most common type of driver head you will find and it looks like a plus sign. When using make sure you have the correct size driver (#1, #2, or #3) or you will easily strip the screw
Square drive – Like the name suggests the driver is in the shape of a square. Some times screws have just a recessed square on the top of the head but other times you can use these drives on “Phillips” heads. Certain screws are combining both the Phillips and square drive so that either can be used.
Torx head – This driver looks like a star with six points. This one is being seen more and more frequently because it has more contact points between the screw and driver than a Phillips head screw.
Allen wrench – This head type is most commonly used on set screws. The shape of this driver is a recessed hexagon. A set screw is most commonly used for holding something in place (wheel on an axle or bit in a counter-sink) or as a depth stop. A set screw can be identified as looking like a tiny bolt with the head cut off. In fact the head is actually the same diameter as the screw’s shank.
Hex head – This is most common on bolts and has a hexagon shape inserted and removed with a wrench or socket.