From The TV IV
Animation features a series of drawings or posed toys or sculptures photographed in sequence to create the illusion of movement, or which uses computer drawings (or "frames") run sequentially. Animation itself dates back to the earliest days of film. Throughout the 1920s, '30s and '40s, animated movies (or "cartoons") were, along with newsreels and movie serials, a part of the daily experience of going to the movies, and most movie houses played several cartoons, often produced by Disney Studios, Warner Bros. or MGM.
Upon the arrival of television in the 1950s, animation in the United States moved almost entirely off the silver screen (excluding feature films, such as those produced by Disney) and to the small screen. Many of the early animated shows were repackaged film shorts, and thus Popeye, Tom and Jerry and the Looney Tunes characters developed a newfound fan following, often decades after their initial cartoons had been produced. Throughout the 1950s and 60s, animated shows played an important role across the American television landscape, and it was not uncommon for such shows as The Flintstones and The Jetsons to air in prime time.
In the late 1960s, the three major American networks—ABC, CBS and NBC—ran programming blocks of animated shows on Saturday mornings from about 7 AM to 1 PM (most commonly 8 AM to 12 PM). These "Saturday morning cartoons" became an American tradition through the 1980s, and as animated shows fell off the prime time slots, they became the primary source of animated shows on television, although many syndicated cartoons such as He-Man and the Masters of the Universe, G.I. Joe and the Transformers were aired by local networks either in the early mornings (6 AM to 9 AM, "before school") or late afternoons (2 PM to 5 PM, "after school") on weekdays. During these decades, animated shows were considered by many to be a genre primarily intended for children.
As television moved into the late 1990s, Saturday morning and after school cartoons largely fell out of favor (although some, such as Batman: The Animated Series and its spin-offs, continued to thrive). NBC even cancelled its Saturday morning line-up altogether. However, the popularity of The Simpsons—the first animated show to find success on a major network in prime time since The Flintstones—as well as the success of other, more adult cartoons on such basic cable networks as Nickelodeon, MTV and Comedy Central and the influx of more serious and dramatic foreign cartoons, largely from Japan, in addition to advances in technology which decreased production costs and an increase in famous animation fans such as George Clooney and Danny DeVito willing to lend their celebrity voices to animated shows, led to a sort of new Renaissance in adult animation. The success also spilled over to children's animation. As a result, more new animated shows are being produced today than at any other point in television history, and their variety has also increased, such that today's array of American animated television fare includes everything from the pop culture parodies of Robot Chicken to the social satire of The Boondocks to the slick, kid-friendly and easily marketable The Emperor's New School to the flashy brashness, surrealism and anarchy of SpongeBob SquarePants to the thrilling action and dramatic moodiness of Justice League Unlimited.
See the Animated shows category for a list of animated shows.