An Ethernet controller is a piece of computer hardware that manages and maintains a computer's connection to a wired network. The Ethernet controller thus plays an integral role in Internet usage and other network functions. A software driver controls the onboard functions of the network device.
Originally, Ethernet controllers were attached to computers via expansion slots, but most computers have network connection ports built into their motherboards as of 2014. Ethernet controllers typically connect at 10 megabits per second, or 100 for a high-speed network. As of 2014, the prevalence of wireless networks has meant that many new devices are dropping the network port in favor of wireless antennas.