Coaxial cables (such as instrument cables) consist of a center conductor wire surrounded by a shield, typically made out of braided copper. The copper shield acts as the return conductor for the signal current and as a barrier to prevent interference from reaching the "hot" center conductor. Unwanted types of interference encountered and blocked with varying degrees of success by cable shielding include radio frequency interference (CB and AM radio transmissions), electromagnetic interference (power transformers) and electrostatic interference (relays and fluorescent lights).

Shielded cables should be used to connect instruments to amplifiers, effects pedals, and mixers. They should not be used to connect amplifiers to speakers.