Make automatic backups
Your Mac comes with software to make backing up simple. Just turn on Time Machine and connect an external drive. Time Machine makes automatic backups of everything so you can recover individual files or your entire system from your backups.
Other backup methods
Store content in iCloud
iCloud lets you store and access your photos, documents, music, and other files in the cloud. iCloud comes with 5 GB of free storage, and you can upgrade your storage any time.
Set up iCloud on your Mac
Copy files to another storage device
If you have an external storage device, you can copy specific files and folders to it any time you want to back them up.
Learn how to find and move filesHow much space do I need for a backup?
To see the size of a specific file or folder, click it once and then press Command-I. To see storage information about your Mac, click the Apple menu in the top-left of your screen. Choose About This Mac and click the Storage tab. For Time Machine backups, it's good to use a drive that has at least twice the storage capacity of your Mac.
Related topics
Free up storage on your Mac
macOS Sierra can save space by storing your content in the cloud. This isn't a backup, but it includes new tools to make it easier to find and remove large or unwanted files before you make a backup.
Use Optimized Storage in macOS Sierra
Erase or format a storage device
You can use Disk Utility if you need to erase or format a storage device.
Learn how to use Disk Utility
macOS Community
Contact Apple Support
Help me with Mac backup
Get help by chat, phone, or email. You can also set up a repair or make a Genius Bar appointment.