The primary method of providing electricity to a laptop is through a plug and socket. The laptop power socket tends to be a through-hole component that is soldered to a circuit board inside the laptop. Laptop power sockets are commonly designed to accept long, cylindrical plugs that slide in and then lock in place. Other varieties use a magnet to hold the power plug in place or have other non-cylindrical designs. A laptop power socket must have at least a terminal and sleeve connector to provide positive and negative contacts, though some include additional terminals to supply electricity for lighted power indicators or other functions.
Laptops are designed to operate on mains electricity, which can either run the devices directly or charge their batteries for portable use. In order to provide electricity to a laptop and its battery, a laptop power socket usually is used. Unlike most desktop computers that include a power supply unit inside the case, laptops tend to have external power converters. These units are designed to convert the mains alternating current (AC) to direct current (DC) that can power a laptop and charge its battery. One end of the AC/DC converter consists of a power plug that can be inserted into the laptop power socket.
There are many laptop power socket designs, and each manufacturer tends to use somewhat different specifications. Most of these sockets are designed to accept a cylindrical plug that has one contact on its outside diameter and another on the inside. In this case, the power socket itself will contain a pin to contact the interior surface of the plug. Other designs resemble a mini Deutsches Institut für Normung (DIN) connector or have a tip-and-sleeve type design. It also is possible for a laptop power socket to use other proprietary means, such as magnets, to connect a plug.
Most laptop power sockets make use of through-hole technology, which means that they are electronic components that can be inserted into holes within a printed circuit board (PCB) and then soldered into place. A great deal of force can be applied to these sockets during normal use, so the terminals that pass through the PCB typically are heavy and thick in construction. The socket also might be bolted to a bracket or other component to keep it from breaking off. This type of breakage can prevent the laptop from operating at all, because the battery will no longer be able to charge.