According to cable engineering, a wire is a metallic conductor used to carry electric current. Wires come in various forms, including solid, stranded, or foil-braided configurations. Based on their insulation, they can be classified as bare wires or insulated wires. The distinction between wires and cables lies in the fact that wires are generally smaller in size and have a simpler structure; however, cables are sometimes categorized as wide wires.

　　Bare wire contains no insulation or protective coating. In addition to serving as a conductor for transmitting electrical energy and signals, it can also be used to manufacture components and connecting leads for electric motors and electrical appliances. Common materials include copper, aluminum, copper alloys, and aluminum alloys.

　　Insulated wires with an insulating coating. They are classified according to application into magnet wire and general-purpose insulated wire. In addition, there are various specialized insulated conductors designed for specific requirements, such as low-voltage automotive wiring, high-voltage ignition wiring for automobiles, lead wires for electrical appliances, aviation wiring, and compensation leads.

　　Cables and wires generally consist of three parts: the conductor, the insulation sheath, and the protective jacket.

　　According to cable engineering, a cable is an insulated conductor consisting of one or more insulated conductive cores enclosed within a sealed sheath. It may be further coated with a protective layer and is used for the transmission and distribution of electrical power or for the transmission of telecommunications signals. The primary difference between a cable and a regular wire is that cables are larger in size and have a more complex structure.

　　Cable engineering defines the main components of a cable as follows: Conductor core: Made of highly conductive materials, such as copper or aluminum. Depending on the laying and service conditions and the required flexibility of the cable, each conductor core may consist of a single wire or multiple wires stranded together. Insulation layer: The insulating material used for cables shall exhibit high insulation resistance, high dielectric breakdown strength, low dielectric loss, and a low dielectric constant. For insulations that are prone to moisture absorption, lead- or aluminum-extruded sealed sheaths are typically employed. Protective coating: Designed to protect the sealed sheath from mechanical damage. Common materials include galvanized steel tape, steel wire, copper tape, and copper wire, which are used as armor to encase the sheath (referred to as armored cable). The armor layer serves to shield the electric field and to prevent external electromagnetic interference.

　　In cable engineering, cables are classified according to their application into power cables, communication cables, and control cables. Compared with overhead lines, cables offer several advantages: smaller inter-conductor insulation clearances, reduced space requirements, the ability to be laid underground without occupying surface space, immunity to environmental pollution, high transmission reliability, and minimal interference with personal safety and the surrounding environment. However, they also have higher costs, more complex construction and maintenance, and more intricate manufacturing processes. Consequently, cables are predominantly used in densely populated areas, regions with highly developed power grids, and locations characterized by heavy traffic; when crossing rivers or laying cables beneath the seabed, they can eliminate the need for long-span overhead lines. Cables are also suitable for applications where overhead lines might cause communication interference, as well as for situations where aesthetic considerations or the avoidance of visual exposure are important.