A socket set is a collection of various types of sockets. They are used for tightening and loosening fasteners. Each type of socket has a specialized purpose. For example, spark plug sockets are used to tighten spark plugs. Others are used to tighten axle nut bolts and ball joints. There are also specialized sockets for certain applications, including penta sockets, which are used for certain vehicles and telephone lines.
Socket sets come with a variety of accessories. For instance, you can find sets with a variety of deep sockets, which are usually smaller and more compact than regular ones. These are useful in automotive environments, but are also popular in non-automotive environments. To find the right socket, you'll need to know if the fastener you're working on uses a standard socket set or deep sockets.
Another tool used to increase the length of a socket is an extension arm. This tool connects to a socket on one end and a ratchet on the other end. This feature allows you to access nuts and bolts that are difficult to reach. Generally, extension arms range from half an inch to 20 inches. They are usually sold separately, but they can be connected to form a longer extension arm. They are often knurled to improve grip.
Hex sockets are the most common type of socket. These sockets have six points of contact with the fastener, making them very versatile. Hex sockets also have a slightly convex internal face that allows you to exert more torque without the risk of stripping the fastener's corners.