Coaxial cables have one conductor insulated with a dielectric material and then surrounded by the other conductor, usually referred to as the center conductor and shield.  Triaxial cables are specialized coaxial cables.  Coaxial cables consist of two cylindrical conductors with a common axis. The two conductors are separated by a dielectric. The outer conductor, normally at ground-potential, acts as a return path for current flowing through the center conductor and prevents energy radiation from the cable. The outer conductor, or shield, is also commonly used to prevent external radiation from affecting the current flowing in the inner conductor. The outer shield or conductor consists of woven strands of wire or is a metal sheath. Triaxial cables are three-conductor cables with one conductor in the center, a second circular conductor shield concentric with the first, and third circular conductor shield insulated from and concentric with the first and second, usually with insulation, and a braid or impervious sheath overall.