A Phillips screwdriver is common in toolboxes, but a Pozidriv is not.
Many people are familiar with the standard flat-head and Phillips screwdrivers, but most people are not familiar with the large variety of other screwdrivers available. Standard screwdrivers will suffice for everyday applications, but for people looking to work with consumer electronics or install screws for tamperproof applications, it might be a good idea to study up on the other tips screwdrivers can have.
Torx
Available in both standard and tamperproof versions, Torx-head screws are commonly found on automobiles and consumer electronics. Both versions are shaped like six-sided stars, but the tamperproof version has a pin in the center of the star. The pin means that a standard Torx-bit screwdriver would not work to install or remove a tamperproof Torx-head screw, but a tamperproof Torx-bit screwdriver could install or remove both kinds of screws. Torx screws are also sometimes referred to as finish-head screws.
Pozidriv
Pozidriv bits are designed to minimize the risk of stripping the screw. Essentially an improved version of the Phillips bit, Pozidriv bits consist of a cross like a Phillips bit, but they also have four more contact points in between to keep the bit from slipping when driving the screw. Pozidriv screws are used in many of the same applications as Phillips bits.
Internal Hex
Internal hex screwdrivers have a hexagonal bit that is inserted into a hexagonal recess in the head of the screw. Screws that use this type of bit are found in assemble-at-home furniture kits and are common in bikes and electronics. Typically, people with experience with this type of screw have used Allen wrenches, but there are screwdrivers made to accommodate internal hex screws. The common size for internal hex screws is 5 mm, but the screws come in a wide range of sizes.
Square Recess
Screws with a square recess, also known as Robertson screws, are designed to keep bits from slipping when driving the screws. These screws are also referred to as trim-head screws, and they are used for finish applications such as installing trim and decking. The bit of the screwdriver and the head of the screw are both tapered so the screw can rest on the driver without being held in place.
Other Bits
There are a variety of other bits as well. Spanner screwdrivers work with security screws that have two slots that pins on the screwdriver are inserted into. Tri-Wing bits are Y-shaped bits frequently used in the production of consumer electronics. Trilobular bits are shaped like rounded triangles and are used in the production of electronics. Each of these bits is designed to discourage tampering.
