The main categories include ordinary screws, self tapping screws and expansion screws three.

There is a head screw Cap screw used to be limited to full tooth fasteners, but this is now not standard usage.

Six angle head screw Hex cap screw with large angle bolt Hex bolt as the name of the head for the six angle of the external thread fasteners, designed to use the wrench rotation. According to ASME B18.2.1 standard, six hexagon head screws (Hex cap screw) six angle bolts general (Hex bolt) of the head and the rod length tolerances, so ASME B18.2.1 six hexagon screws for installation can be used in all six angle bolts in place, also contains six angle bolts too large to be used place. Six hexagon head screws Socket cap screw also known as the Aaron screw or bolt Wotou (Allen bolt), is the head of the screw has a six angle hole, six square (hex key, Allen wrench or Allen key) inserted into the inner hole to tighten or loosen. In the six corners of the most commonly used screw cylindrical head screws, head diameter of about 1.5 times the diameter of the main thread (1960 series), other type including half round screw surface (Bottom head cap screw appearance) and apply flat screw on taper screw hole (Countersunk head cap screw). The design of the screw hole allows the screw head not to be exposed on the surface of the object to be fixed, and therefore, the utility model can be used in places where the surface is small and the traditional spanner is inconvenient to use.

Machine screw Machine screw is generally less than &frac14 in diameter; inch screw (4#~12#), usually for the entire tooth and rotation by the screwdriver, such as word slotted, cross, or six corners, etc..