NBC got its start in 1926 as the nation's first radio network. Its parent company, the Radio Corporation of America, figured people would buy the radios it made if they had interesting things to listen to.
The network began television broadcasts in 1939 and produced TV's first star in Milton Berle in 1948. Though it faced fierce competition over the decades, NBC was formidable in the 1990s, with Thursdays declared a "must-see" night of television.
Lately, NBC has been sagging in fourth place, struggling to find a hit.
Other properties that are part of NBC Universal have struggled, too. The Universal movie studio has had notable flops such as the Judd Apatow comedy "Funny People," and theme park attendance fell in the recession.
The bright spot is in such cable channels as USA, Syfy, Bravo and CNBC. Cable TV operator Comcast has its sights on those. It wants to diversify its holdings to stave off encroaching threats from online video and rival subscription-TV providers.