Hydro One operates as an electricity transmission and distribution company in Ontario. The company operates through three segments: Transmission, Distribution, and Other. It owns and operates approximately 30,000 circuit kilometers of high-voltage transmission lines and approximately 125,000 circuit kilometers primary low-voltage distribution lines. The company serves residential, small business, commercial, and industrial customers, as well as municipal utilities. It also provides telecommunications support services for its transmission and distribution businesses; and information and communications technology services and solutions.