Discovery Communications, Inc. operates as a non fiction media company worldwide. It operates through three segments: U.S. Networks, International Networks, and Education. The company provides original and purchased content across various distribution platforms. Its content covers genres, including science, exploration, survival, natural history, technology, docu-series, anthropology, paleontology, history, space, archeology, health and wellness, engineering, adventure, lifestyles, forensics, civilizations, current events, and kids. The company owns and operates nine national television networks in the United States, including Discovery Channel, TLC, Animal Planet, Science Channel, Investigation Discovery, Military Channel, Planet Green, Discovery Fit & Health, and Velocity. Discovery Communications also has interests in Oprah Winfrey Network, a pay-television network and Website; The Hub that features original programming, game shows, and live-action series and specials; and 3net, a three-dimensional network. In addition, it offers network branded Websites, and mobile and video-on-demand services; and distributes various national and pan-regional television networks. Further, the company develops and sells curriculum-based products and services to public and private K-12 schools, such as access to an online video on demand service that includes curriculum-based tools, professional development services, digital textbooks, and student assessment and publication of hardcopy curriculum-based content. As of December 31, 2012, it operated approximately 180 distribution feeds in 40 languages. The company is headquartered in Silver Spring, Maryland.