View source for Essential things to know before you start

Learning computer networking is not horribly difficult but it does require some initial understanding of the electrical components required to make networking 'work.'

*''' Wire '''
::The most common kind of wire used for computer networking today is called "category 5" or "category 6", abbreviated as cat5 or cat6. This wire is specifically designed to carry low voltage digital signals over a distance between a sending network device and a receiving device. You cannot substitute speaker wire or other kinds of wire in its place because the 8 wires that are inside a jacketed cat5 cable are paired, and each pair is twisted together at different twist intervals to help minimize noise and interaction between wire pairs. Cat5 cable contains either solid core wire or stranded wire, but in either case, the gauge of the wire is generally 24 gauge and has very thin insulation. Because it's rather tiny wire and does not have much insulation, cat5 wire is not a good choice for carrying high current or voltage loads. Cat5 wire uses plastic "crimp" plug connectors on the ends, making it easy to plug network devices together. 

:::'''Extremely important:''' Just because a cable has a cat5 crimp plug on the end, or because a device has a jack that looks like a cat5 plug can plug into it, do not automatically assume that it is a network connection or a network device. This hobby uses cat5 cable for both networking and for other low-voltage electrical connections between devices that are NOT actual network devices but may be serial communications and/or TTL signaling between various lighting equipment. Before plugging something in, find out what kind of devices are involved first.

::Another kind of networking wire is coaxial wire, which is similar to TV coax cable. Generally RG58U is used, but because category 5 wiring is so much easier, less expensive and provides more options, coax is rarely used anymore. A coax-based network is typically called a 10-base-2 network and uses T-connectors and 50-ohm terminators to connect devices together. A serious drawback to 10-b-2 is that if a break in the network wire occurs, all the computers on that wire go down.

*''' Switches and Hubs '''
:: To have a network of multiple devices, one generally needs a way to interconnect them. Interconnections are the work of a network switch or network hub. Either device usually requires power, which is usually provided by a simple wall wart. There's a difference between the two devices and it's important to know the difference. Almost exclusively these devices provide connections via RJ45 plugs and cat5 wiring.
::: '''SWITCH:''' This is the preferred device, is generally faster and is 'smart' in the sense that it remembers the connections between devices and automatically reconnects them for increased efficiency and communication speed.
::: '''HUB:''' This provides the same plug-in convenience that a switch does but it does not have the 'smart' electronics to remember connections. Consequently, traffic going through a hub has to search for and reestablish connections as needed which generally creates more network traffic which usually results in slower overall network performance.