Cablevision Systems Corporation (NYSE: CVC) is an American cable television company with systems serving areas surrounding New York City. It is the 8th largest cable provider in the USA, with most customers residing in New York, New Jersey, Connecticut, and parts of Pennsylvania. Cablevision also serves approximately 300,000 customers in Colorado, Montana, Utah, and Wyoming under the Optimum West brand. Cablevision also offers high-speed Internet connections (Optimum Online), as well as digital cable (iO), and VoIP (Optimum Voice) phone service (the 8th largest telephone provider in the U.S.) through its Optimum brand name.

Cablevision was founded by Charles Dolan in 1973. In the mid-1960s, Dolan had already built a cable system called Sterling Manhattan Cable in the borough of Manhattan and launched Home Box Office (HBO). He ended up selling both the cable system and HBO to Time Life Inc. With the money he gained from the sale, he started a new cable system in suburban Long Island forming Cablevision. Cablevision quickly expanded and built system throughout the New York metro area expanding into New Jersey, Westchester County, Connecticut, and the other boroughs of New York City.