Skype grew into one of the most widely used calling and messaging apps of the 2000s and 2010s, and its short notification chimes became part of everyday online communication for millions of users. The new message sound was designed to be heard at a glance, alerting someone to an incoming chat without interrupting a call or work. As Skype use declined and other apps took over, the sound lived on in memes, reaction videos and retro tech compilations, where it instantly signals an old-school chat era and a message arriving out of the blue.