There are two main types of audio cable we will look at: Single core / shielded (unbalanced) and One pair / shielded (balanced).
Single Core / Shielded Cable

In a single core / shielded cable, the single core is used for the +ve, or 'hot', and the shield is used for the -ve, or 'cold'.
This type of cable is used for unbalanced audio signals.

Single core / shielded cable
One Pair / Shielded Cable

A one pair / shielded cable has one core as the +ve, and the other core is -ve. The shield is earthed.
This type of cable is used for balanced audio signals.

One pair / shielded cable