- The Twillight Zone
The Twilight Zone is an American television anthology series created by Rod Serling. Each episode (156 in the original series) is a mixture of self-contained drama, psychological thriller, fantasy, science fiction, suspense, or horror, often concluding with a macabre or unexpected twist. A popular and critical success, it introduced many Americans to serious science fiction and abstract ideas through television and also through a wide variety of Twilight Zone literature. The program followed in the tradition of earlier shows like Tales of Tomorrow (1951–53), which also dramatized the short story "What You Need", and Science Fiction Theatre (1955–1957). As well as radio programs such as The Weird Circle and X Minus One and the radio work of Serling's hero, dramatist Norman Corwin. Serling himself was a fan of anthology pulp fiction stories as a little boy and as an adult, he wished to write of social commentary themes such as racism, government, war, society and human nature in general. He decided to combine the two so he could not only indulge both of these passions, but also to get away with talking about these on television at a time when TV wasn't allowed to address such things.
The series was produced by Cayuga Productions, Inc. a production company owned and named by Serling. It reflects his background in upper New York State and is named after the local Lake Cayuga where Cornell University is located.
The success of the original series led to the creation of two revival series: one series that ran for several seasons on CBS and in syndication in the 1980s, and another series that ran on UPN from 2002 to 2003. It also led to a feature film, a radio series, a comic book, a magazine and various other spin-offs that spanned five decades.
Aside from Serling himself, who crafted nearly two-thirds of the series' total episodes, writers for The Twilight Zone included leading genre authors such as Charles Beaumont, Richard Matheson, Jerry Sohl, George Clayton Johnson, Earl Hamner, Jr., Reginald Rose, Harlan Ellison and Ray Bradbury. Many episodes also featured adaptations of classic stories by such writers as Ambrose Bierce, Lewis Padgett, Jerome Bixby and Damon Knight.
The term "twilight zone" predates the television program, and originally meant the middle layer of the world's oceans that receives only faint, filtered sunlight during the daytime. This is because the seawater absorbs the sunlight. 
Sources : http://en.wikipedia.org/wiki/The_Twilight_Zone