This sound comes from The Flash, the CW television series that began in 2014. Its recognizable theme music became popular beyond the show because short clips of heroic TV scores work well in fan edits, meme videos and character introductions. Online, people use this cue to signal speed, urgency or a classic superhero moment without needing any dialogue. Its staying power comes from how quickly viewers connect the music with Barry Allen and the fast-paced style of the series.