Ethernet adapters are a type of network interface controller that can allow computers and other devices to connect to a local area network (LAN). The main use of the term refers to a hardware component that allows a device to network using a category five (cat5) or six (cat6) twisted pair cable. These Ethernet adapters are typically based on either expansion cards or universal serial bus (USB). A wireless Ethernet adapter is a similar piece of hardware that can connect to the an existing Ethernet jack in order to provide a device with Wi-Fi™ connectivity.
Some motherboards come equipped with Ethernet hardware and do not require additional adapters, while others lack this functionality. If a motherboard does not have a built-in Ethernet jack, it is often possible to upgrade it. Many computers have a number of spare expansion slots into which Ethernet adapters can be installed. Some laptops have the same type of option in the form of ExpressCard® or similar expansion slots. If a laptop has one of these slots, it is often possible to plug in an Ethernet adapter.
USB Ethernet adapters can be used with either desktop or laptop computers, often regardless of the operating system (OS). In their simplest form, these Ethernet adapters look like a female Ethernet jack connected to a male USB plug. A more complicated type of USB Ethernet adapter is the hubs, which may provide a number of additional USB connections in addition to an Ethernet jack. These Ethernet adapters typically function in much the same way as those contained on expansion cards, and may be used to connect the computer to a LAN or various devices.
Wireless Ethernet adapters offer a slightly different functionality. Instead of adding an Ethernet jack to a computer, these devices use an existing connection to add wireless functionality. Many Wi-Fi® adapters and dongles plug into a USB port, which devices like video game consoles and printers may lack. Since these adapters can connect to a standard Ethernet port, they may allow these network ready devices to connect wirelessly instead of with a physical cable.
Each of these different kinds of Ethernet adapters have the same basic purpose of connecting computers or devices to a network. This can allow an Internet connection to be shared, files to be send or received, or devices like printers to be accessed. If a printer is connected to the network either physically or wirelessly, each other networked computer will usually be able to print to it. Other devices, such as remote hard drives and media center extenders, may also be shared in this manner.