Apple used this unlock sound on iPhones during the 2009 to 2016 period, when the lock screen click became one of the most recognisable sounds of the early smartphone era. As old iPhones were replaced and later software removed the sound, clips of it began circulating online as a piece of tech nostalgia. It survives today because it is instantly recognisable to anyone who owned an iPhone in that period, and it immediately sets a scene in the late 2000s or early 2010s without needing any explanation.