Comcast corporation, headquartered in philadelphia, is the largest american multinational telecommunications conglomerate. It is the second-largest broadcasting and cable television company in the world by revenue (behind at&t), the largest pay-tv company, the largest cable tv company and largest home internet service provider in the united states, and the nation's third-largest home telephone service provider. It provides services to u. S. Residential and commercial customers in 40 states and the district of columbia. As the parent company of the international media company nbcuniversal since 2011, comcast is a producer of feature films for theatrical exhibition, and over-the-air and cable television programming.