For the first 15 years of Classic Mac OS, right up to Mac OS 9 in 1999, Macs remained fundamentally single-user, and privacy wasn’t an issue of much concern. In those halcyon years of desktop publishing and HyperCard, users were more excited by opening information up than keeping it private, and the internet was in its infancy. It was Mac OS 9 that first integrated multiple user accounts and started to secure information using keychains. Mac OS X brought the first full multi-user operating syste...