Ready to start backing up your Mac? You don't need anything but an external hard drive and OS X's built-in Time Machine.
If you value your data—whether it’s some perfect photos you took last weekend, your entire music collection on iTunes, or your draft of the next great American novel—you must stay on top of regular system backup. One of the easiest ways of doing so is to use OS X’s built-in backup program, Time Machine. Time Machine works with your Mac and an external drive to save important documents, photos, and system files regularly. Apart from keeping spares of every file, Time Machine maintains a record of how your system looked on any given day, so you can easily put everything back the way it was if something goes wrong.
OS X has included Time Machine since OS X 10.5 (Leopard). Here’s how to get set up in OS X 10.8 (Mountain Lion) using an external drive. For more tips on backing up your data, see "Backup basics" and "Bulletproof backups."