Discovery Communications, Inc. is an American global mass media and entertainment company based in Silver Spring, Maryland. The company started as a single channel in 1985, The Discovery Channel. Discovery also is a provider of educational products and services to schools, including a series of K-12 digital textbooks, through Discovery Education, and Discovery Digital Networks. DCI both produces original television programming and acquires content from producers worldwide. This non-fiction programming is offered through DCI's 54 network entertainment brands, including Discovery Channel, American Heroes Channel, TLC, Animal Planet, Investigation Discovery, Velocity, Discovery Life and a family of digital channels. Despite being publicly traded on the NASDAQ stock exchange, the Newhouse family exercise the largest stake in the company, 31%, through privately held Advance Publications. Discovery Digital Network shows are offered through multiple services, including Revision3.com, Animalist.com, TestTube.com, PhillyD.tv, Sourcefed.com, YouTube, iTunes, and more than 40 other distribution partners and devices. Discovery has 300 monthly online streams of its programming.