Screws vary considerably in terms of size, purpose, and quality. Some are purely functional, and their appearance is of no importance; others have an aesthetic role as well as a practical one. Once you have chosen the most appropriate screws for your project, check that you have the correct screwdriver to drive them. Screw heads are quickly damaged by the wrong screwdriver, so always use the correct size — it also makes the job easier.

Head Design

Screws are designed to be turned by particular types of screwdrivers. You can tell which type to use by looking at the pattern of slots in the top of the screw head. Some modern screws have unusual head designs that require special bits rather than traditional screwdriver designs.

Flat Head
Traditional design with a single slot crossing the diameter of the screw's head.

Courtesy of DK - Do It Yourself Home Improvement © 2010 Dorling Kindersley Limited

Phillips
Cross-headed, with two slots bisecting one another. The slots are deeper in the center.

Pozidriv
A cross-head screw similar to the Phillips, but with smaller divisions between the cross' slots.

Dual-Purpose
Some screws combine head types. This example has both a Phillips head and a flat head.

Hexagonal-Headed
Hexagonal (hex) screws need to be tightened with a hex screwdriver or bit.

Square-Headed
These are also inserted with a special screwdriver or bit.

Security
Similar to a standard screw except that once inserted, it cannot be removed.

Courtesy of DK - Do It Yourself Home Improvement © 2010 Dorling Kindersley Limited