Copper Cabling: Twisted Pair and Coaxial

Twisted Pair Cable: The Ethernet Standard

Twisted pair cable consists of pairs of copper wires twisted together, which is exactly what most Ethernet cabling (the kind connecting most home and office devices) is built from.

Why the Wires Are Actually Twisted

Straight wires:  ----------------   ----------------   (prone to picking up interference together)
Twisted pair:     )( )( )( )( )(     )( )( )( )( )(     (twisting cancels out much of the interference)

Twisting the wire pairs together causes electrical interference picked up by each wire to largely cancel itself out, since both wires in a pair pick up very similar interference and their signals are compared differentially - a deliberate, simple, and effective design.

Unshielded vs Shielded Twisted Pair

Cable Categories: Cat5e, Cat6, and Beyond

Ethernet twisted pair cables are rated by category (Cat5e, Cat6, Cat6a, and so on), with higher numbers generally supporting higher maximum speeds and better interference resistance - the physical cable itself is the limiting factor for how fast a wired connection can actually run.

Coaxial Cable: A Different Structure

Coaxial cable uses a single central copper conductor surrounded by insulation, a metallic shield, and an outer jacket - all layered concentrically ("co-axial," sharing the same axis). It's less common for modern computer networking today, but still widely used for cable television and cable internet connections.

Why Fiber Is Gradually Replacing Copper for Long Distances

Copper cabling of any kind suffers from signal degradation over longer distances and is more susceptible to electrical interference than fiber optic cable, covered in the next note - which is why fiber has become the preferred choice for longer runs and high-capacity backbone connections.