To keep your files safe, it’s important to back up your regularly. The easiest way to back up is to use Time Machine—which is built into your Mac—to back up your apps, accounts, preferences, music, photos, movies, and documents (it doesn’t back up the macOS operating system). Use Time Machine to back up to an external storage device connected to your , or to a supported network volume. For a list of devices supported by Time Machine, see the Apple Support article Time Machine troubleshooting on Mac in the macOS User Guide. Also see the Apple Support article What to do before you sell, give away, or trade in your Mac.