CAT-5

                                         CAT-5 Cable

The sort of cable running in any network is called a
Category 5 cable for Ethernet, or CAT-5 cable. It has two distinguishing
features. First of all, it has an unshielded twisted pair cable or UTP cable.
Secondly, it takes an RJ-45 connector on either end. Most Ethernet
networks run on CAT-5 cables.
CAT-5 cables have print on the outside giving you important information
about the cable. As an example, you can look on the outside of the cable to
see what type it is, what the speed is, and any relevant standards.

The CAT-5 cable dissected

If you open up a CAT-5 cable, you’ll find eight colored wires
twisted into four pairs. One pair is brown, another pair is
blue, another pair is green, and the final pair is orange. Each
pair consists of one plain and one striped wire.

So why are the pairs twisted?

The problem with wires that aren’t twisted is that they generatmagnetic fields that interfere with the signal carried on the wire. This means that you can get electromagnetic interference and crosstalk—
both of which are bad for your network data.
When the wires are twisted, the magnetic field around the wire is
effectively disrupted so that any interference is reduced. The more
twists there are in the pairs, the better.