Unfortunately this is not actually a machine that can take you back through time (let’s say back to 1959, where you could buy a dozen Sunburst Les Paul Standards at mere $280 each). This is actually the name of a feature in Apple’s Mac OS X 10.5 “Leopard” operating system that backs up your system files, applications, accounts, preferences, music, photos, movies and other documents. What makes Time Machine different from other backup software is that it not only keeps a spare copy of every file, it also remembers how your system looked on a given day, so you can revisit your Mac as it appeared in the past. It makes hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for everything older than a month. For the initial backup, Time Machine copies the entire contents of the computer to your backup hard drive, skipping caches and other files that aren’t required to restore your Mac to its original state. Every hour, every day, an incremental backup of your Mac is made automatically as long as your backup drive is attached to your Mac.