This is a type of signal transmission cable.
It has a thin copper core/wire about a millimeter thick. The core is separated from the outer sheath by some plastic spacers to keep the core in the centre of the cable at all times. This is why you can't bend the coaxial too much without kinking and damaging it.
The outer sheath is braided copper. So effectively it looks like a tube within a tube.
Co-axial cable is excellent for carrying radio signals. The lead going from the television aerial to your television is a co-axial cable. The lead from the satellite dish to the receiver is a co-axial cable.
Some data transmission cable is co-axial, although it is used less these days for that, as twisted-pair and fibre-optic cables are more popular.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Co-Axial Cable