Dialup modems connected home computers to the internet over telephone lines, and the screeching handshake was simply the sound of the modem and the provider exchanging data to agree a speed. In the Windows 95 and Windows XP era that noise was a daily ritual before browsing, gaming or downloading a single song. As broadband replaced dialup, the clip survived as nostalgic shorthand online, filed alongside the error sound and other retro PC noises, and creators now use it whenever modern tech needs to feel ancient.