ICQ was one of the first widely used instant messaging services, launched in 1996 and popular through the late 1990s and early 2000s for real-time chats, contact lists, and status messages. Its short notification sounds became instantly familiar to millions of early internet users, and later resurfaced in YouTube videos, streams, and meme edits as shorthand for an old-school message arriving. Today it works as a compact nostalgia cue, instantly signalling a simpler era of online chat.