In order for a PC to connect to a computer network it needs a special piece of hardware called a network interface card or NIC. This hardware is responsible for communicating messages onto the network. Each type of network will use different types of NIC's. For example a wireless network requires a wireless NIC. A token ring network NIC would not work on an Ethernet network etc. NIC's tend to be less common as they tend to be built into most modern motherboards. However this will normally be a simple Ethernet connector. If you require token ring you would have to install a separate NIC.