IEEE standards for LANs describe different types of transmission media. It could be cable,
fiber or wireless.
Cables typically come in two flavors: twisted pair cables or coaxial cables.
Twisted pair cables
A twisted-wire consists of two insulated strands of copper wire that have been braided.
Often a number of twisted-wire pairs are grouped together into a twisted pair cable. Twisted
pair cables are used both for data communication and telephony.
In the picture the twisted pair cables would typically be used in the star topology in the
middle, that is between the hub and the connected hosts.
Coaxial cables consist of a central conducting copper core that is surrounded by insulating
material. The insulation is surrounded by a second conducting layer, which can consist of
either a braided wire mesh or a solid sleeve. In the picture, the coaxial cable would typically
be used for the bus network seen on the top.
Optical fibers can be used to carry data signals in the form of modulated light beams with
high bandwidth. An optical fiber consists of an extremely thin cylinder of glass, called the
core, surrounded by a concentric layer of glass. In the picture, the optical fiber would
typically be used for the backbone network.
Different types of radio LANs are available on the market. This is an expensive type of
LAN technique. In the picture, wireless connection is used between the two hosts with
antennas. Wireless LAN connections are often used in old historical buildings where you are
not allowed to install cables.