The CW is a joint venture between the CBS Corporation and Warner Bros. Entertainment - that's where the C and the W in the network's name come from - and perhaps thanks to the size and industry power of its parent corporations, it's currently the world's fourth-largest broadcast network. CW programming is geared toward a young adult audience, and its original series have, in recent years, begun to attract audience sizes that approach those of some Big Three network series.
The CW is the successor to the UPN and WB networks, youth-oriented broadcast networks backed by media juggernauts Paramount and Time Warner, respectively. Those two networks stopped broadcasting in 2006 and were immediately replaced by the CW. The network broadcasts on affiliate stations in both the United States and Canada.
CW original programming, which broadcasts on week nights, is aimed at viewers between 18 and 34 years old, the demographic most prized by advertisers. The network's earliest programming included reality series such as "America's Next Top Model" and "WWE Fridany Night Smackdown," a staple of its predecessor networks.
The CW's biggest rating successes, though, have come via its original drama programming. "Gilmore Girls" (which began on the WB), "7th Heaven," "Smallville," "Gossip Girls" and others all generated significant buzz, and current series "The Vampire Diaries" (along with its spin off, "The Originals") and "Arrow" consistently post strong ratings.