What does the twist in the Cat5 cable do?
The Category 5 cable consists of 8 conductors, creating 4 pairs of wires. Each pair is created by twisting the two wires around each other along the full length of the cable. This is done in order to eliminate crosstalk and any other type of interference the cable might pick up from near by electrical sources.
Laws of physics state that when current (electricity) passes through a wire, it will create an electric field around it. The more current, the larger the electric field will be.
If at the same time you place another wire (I.E. network cable) near the field, it is likely to 'pickup' noise from that field and possibly create abnormal current patterns on it.
Because we want out network cable to be immune to these effects, the twist was introduced, effectively canceling any interference picked up by any wire in the pair.