ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority (ITA) to provide competition to the BBC. CITV is part of the ITV Network.
Since the passing of the Broadcasting Act 1990, its legal name has been Channel 3, the number 3 having no real meaning other than to distinguish it from BBC One, BBC Two and Channel 4.
In part, the number 3 was assigned as televisions would usually be tuned so that the regional ITV station would be on the third button, the other stations being allocated to the number within their name.