What is coaxial cable and what are its common uses?

Coax is a single copper conductor wrapped in insulation, then a copper braid/foil that doubles as shield and second conductor, then a jacket; used for cable internet/TV and as an antenna feed line.

The name "coaxial" comes from its layout: the two conductors share the same axis, one nested inside the other. From the inside out, coaxial cable has four components:

* Working inward: outer jacket, copper braid/foil shield (also the second conductor), plastic insulation, and the inner copper conductor that carries the signal. *

1. Copper conductor — the inner wire that actually carries the electronic signal.
2. Flexible plastic insulation — separates the inner conductor from the outer shield.
3. Woven copper braid or metallic foil — does double duty as the second conductor of the circuit and as a shield against interference.
4. Outer cable jacket — prevents minor physical damage.

That built-in shield is what lets coax carry signals well over distance with good noise rejection. Its common uses are:

• Cable internet and cable TV — the customer-premises wiring from the provider to the home.
• Older Ethernet / bus networks — early LANs (10BASE2/10BASE5) ran on coax.
• Antenna feed lines — connecting an antenna to a wireless device. Note this is still a wired link carrying the antenna's signal; coax itself is not a wireless medium.

Connector types: BNC, N-type, and F-type (the F-type is the screw-on connector you see on a TV/cable-modem coax).

Go deeper:

• Coaxial cable — Wikipedia — the concentric construction and its wired uses: cable TV, broadband internet, and radio/antenna feed lines.

• Fiber vs twisted-pair vs coaxial cable — FS.com — where coax sits against the other two wired media.