Files can be lost when your Mac’s internal storage develops a fault, gets corrupted, or if you accidentally trash a file. OS X’s Time Machine feature offers protection against such events by backing up new and modified files once an hour. All you need to provide is an external hard drive.
It won’t help recover files that are created and trashed within that interval, but multiple versions of other files on your Mac are preserved while there’s free space available. As it diminishes, the number of old versions is trimmed, but you can always connect a fresh drive.
In the long term, it’s worth complementing Time Machine with an off-site backup plan to protect against physical damage or theft of all your hardware. But for day-to-day mishaps, and even serious faults, Time Machine can quickly get you out of a sticky situation. Here’s how to set it up.
Complete Guide to Time Machine