Overhead wires are often used to conduct electricity for trains, trams, and other transportation systems. Synonyms for overhead wire include catenary wire, contact wire, trolley wire, and pantograph wire. Catenary wires are used primarily for electric trains and are suspended from a support structure. Contact wires are used for trams and are affixed to poles and tensioned between them. Trolley wires are used for electric buses and are typically supported on overhead gantries. Pantograph wires are used for high-speed trains and are attached to a pantograph, a device that allows electric trains to move at high speeds without losing contact with the wire. Whatever the name, these wires play a crucial role in powering modern transportation.