Transceivers are also referred to as Medium Access Units (MAUs). They are used to connect nodes to the various Ethernet media. Most computers and network interface cards contain a built-in 10BASE-T or 10BASE2 transceiver which allows them to be connected directly to Ethernet without the need for an external transceiver.
Many Ethernet devices provide an attachment unit interface (AUI) connector to allow the user to connect to any type of medium via an external transceiver. The AUI connector consists of a 15-pin D-shell type connector, female on the computer side, male on the transceiver side.
For Fast Ethernet networks, a new interface called the MII (Media Independent Interface) was developed to offer a flexible way to support 100 Mbps connections. The MII is a popular way to connect 100BASE-FX links to copper-based Fast Ethernet devices.