Socket screws are a type of screw designed and manufactured with a hexagonal (hex) internal drive built into the head. As such, they are intended to be tightened and loosened with an Allen wrench or hex key, as opposed to a traditional screwdriver. This is the key feature that sets a socket screw apart from other screw head drive styles such as the Phillips head screw, slotted and flathead screws, and Pozidriv screws, to name just a few.
Another common distinction is that socket screws are often squared off at the tip. These are generally referred to as flat point socket screws and they tend to be the most widely used type found in many common applications. However, it's worth noting that various other designs are also available.
In most other regards, there isn’t typically much physical difference between socket screws and regular screws for the majority of everyday uses. So what exactly is the point of a socket screw, and when should you use one?
In short, socket screws combine some of the increased performance features of other common hex fasteners - nut and bolt systems being the obvious point of reference - with the convenience and ease of use of a standard format screw set. This middle ground can be a useful compromise in many situations, particularly when working in confined spaces or areas without easy access to secure externally wrenched hex fasteners.