Comcast Corporation (formerly registered as Comcast Holdings)[note 1] is an American global telecommunications conglomerate that is the largest broadcasting and cable television company in the world by revenue (through its Xfinity brand).[4] It is the second-largest pay-TV company after AT&T, largest cable TV company and largest home Internet service provider in the United States, and the nation's third-largest home telephone service provider. Comcast services U.S. residential and commercial customers in 40 states and in the District of Columbia.[10] The company's headquarters are located in Philadelphia, Pennsylvania.[11] As the owner of the international media company NBCUniversal since 2011,[12][13][14][15] Comcast is a producer of feature films and television programs intended for theatrical exhibition and over-the-air and cable television broadcast.