Hanna-Barbera was the animation studio founded by William Hanna and Joseph Barbera that defined American television cartoons, creating The Flintstones, The Jetsons, Scooby-Doo and many other Saturday morning favorites. Its production logo closed countless episodes, so the short sting became shorthand for that whole era of animation. Decades later, creators reuse it online as a nostalgic sign-off, a retro intro for cartoon compilations and a quick cue that a clip belongs to classic TV history rather than a modern show.