What backing up your computer actually means

Backing up your computer means making a copy of the files and settings that matter to you — your documents, photos, email, browser bookmarks, installed programs — and storing that copy somewhere separate from your computer. If your hard drive fails, you get hacked, your computer is stolen, or malware wipes your files, you still have them.

The key word is separate. A backup on the same computer, or on an external drive sitting next to it, does not protect you if the computer itself is destroyed or stolen. A real backup lives somewhere else: on a cloud service, on a drive you keep in another location, or ideally both.

Most people need two things: an automatic backup that runs without them thinking about it, and a way to restore specific files if they delete something by accident. This guide covers both.

Key Takeaways

  • A backup only protects you if it is stored somewhere separate from your computer — on a cloud service, an external drive kept elsewhere, or both.
  • Windows includes File History (built-in, free, backs up to an external drive) and System Image (a complete copy of your entire computer at one moment in time).
  • Mac includes Time Machine (built-in, free, backs up to an external drive) and iCloud (cloud backup, limited free storage, requires an Apple account).
  • Cloud services like OneDrive, Google Drive, and Dropbox back up automatically but only cover files you put in their folders, not your entire computer.
  • The safest setup uses two methods: one automatic cloud backup for daily protection, and one external drive backup you update monthly or quarterly.

Windows built-in backup: File History and System Image

Windows comes with two free backup tools. File History backs up your documents, photos, music, and videos to an external drive on a schedule you set. System Image creates a complete snapshot of your entire computer — every file, every setting, every installed program — at one moment in time. If your computer stops working, you can restore from the System Image and be back where you started.

To set up File History: plug in an external drive, open Settings, go to System, then Backup. Turn on "Backup with File History" and choose your external drive. Windows will then back up automatically every hour by default. You can change how often in the same menu. File History keeps multiple versions of your files, so if you delete something by accident, you can restore an older version from weeks ago.

To create a System Image: open Control Panel, go to System and Security, then Backup and Restore (Windows 7). Click "Create a system image" on the left. Choose your external drive as the destination. This takes longer — usually 30 minutes to an hour — but it captures everything. Store this drive somewhere safe, separate from your computer. If your hard drive fails, you can boot from a Windows recovery drive and restore the entire System Image to a new drive.

Mac built-in backup: Time Machine and iCloud

Time Machine is Mac's version of File History. Plug in an external drive, open System Settings, go to General, then Time Machine, and click "Add Backup Disk". Select your external drive. Time Machine then backs up automatically every hour, keeping hourly backups for 24 hours, daily backups for a month, and weekly backups for all previous months. Like File History, you can restore individual files or your entire Mac from any point in time.

iCloud is Apple's cloud backup service. It backs up your photos, documents, email, and settings to Apple's servers automatically if you turn it on in System Settings under your Apple ID. The free tier includes 5 GB of storage, which fills quickly if you have many photos. You can pay for more storage (50 GB, 200 GB, or 2 TB per month), but iCloud does not back up your entire computer the way System Image does — only specific file types and settings.

The best Mac setup combines both: Time Machine to an external drive for a complete backup you control, and iCloud for cloud protection of your most important files. Keep the external drive in a different location from your Mac — at a friend's house, in a safe deposit box, or in your office.

Cloud services: OneDrive, Google Drive, Dropbox, and others

Services like OneDrive (Microsoft), Google Drive (Google), Dropbox, and iCloud Drive back up files automatically, but only files you put in their designated folders. They do not back up your entire computer, your installed programs, or your system settings. They are useful as a second layer of protection for documents and photos you care about, but they should not be your only backup.

OneDrive comes free with Windows and includes 5 GB of storage. Files you save to your OneDrive folder sync to Microsoft's servers automatically. Google Drive offers 15 GB free and works on Windows and Mac. Dropbox offers 2 GB free. All three let you access your files from any device and restore deleted files for 30 days (longer if you pay for a plan).

The advantage of cloud services is that they run in the background without you plugging in a drive. The disadvantage is that they only cover files you actively move into their folders. If you keep documents on your Desktop or in a custom folder, they will not back up unless you move them. Also, if malware encrypts your files or a hacker deletes them, the cloud service may sync those changes and overwrite your backup. Most cloud services let you restore deleted files for a limited time, but that is not the same as a full system backup.

External drives: what to buy and how to use them

An external hard drive is a portable storage device you plug into your computer via USB. They range from $50 to $200 depending on size. For most people, 1 TB to 2 TB is enough. Brands like Western Digital, Seagate, and LaCie are widely available and reliable.

Buy two external drives if you can afford it. Use one for your regular backups (File History, Time Machine, or cloud sync). Keep the other in a different location — at work, at a friend's house, or in a safe deposit box — and update it every few months. This protects you if your computer and your primary backup drive are both destroyed or stolen at the same time.

External drives fail eventually, usually after 3 to 5 years of regular use. Replace yours if it is older than that, or if you hear clicking sounds or see error messages about the drive. Do not wait until it stops working entirely.

What to do if your computer fails or gets hacked

If your hard drive fails and your computer will not start, you can restore from a System Image (Windows) or Time Machine backup (Mac). You will need a recovery drive — a USB stick with Windows or Mac recovery software on it — which you can create before anything goes wrong. On Windows, search for "Create a recovery drive" in Settings. On Mac, restart while holding Command-R to enter Recovery Mode, then use Restore from Time Machine Backup.

If you get hacked or infected with malware, restoring from a backup is often the safest way to clean your computer. However, restore from a backup that is older than the infection — ideally from before you noticed anything wrong. If you only have recent backups, the malware may be in them too. This is why keeping backups from different points in time matters.

If files are encrypted by ransomware, do not pay the ransom. Disconnect your computer from the internet when ready to stop the malware from spreading. Then restore from your oldest available backup. If you have no backup, contact the FBI's Internet Crime Complaint Center (IC3) at ic3.gov for guidance.

How often to back up and what to back up

Automatic backups (File History, Time Machine, cloud sync) should run continuously or at least daily. You do not need to do anything — they happen in the background. Manual backups (System Image, external drive copies) should happen at least quarterly, or monthly if your files change frequently.

Back up everything: your documents, photos, videos, email, browser bookmarks, and any files you have created or downloaded. Do not back up operating system installation files or large program installers — you can read those again if you need them. Do not back up temporary files or cache folders, which take up space and are not important.

If you have a lot of files and limited backup space, prioritize: documents and photos first, then email and browser settings, then everything else. A partial backup is better than no backup.

Frequently Asked Questions

Can I back up to a cloud service instead of an external drive?

Yes, but only for files in that service's folder. OneDrive, Google Drive, and Dropbox all back up automatically to the cloud. The trade-off is that they do not back up your entire computer, your installed programs, or your system settings. Use cloud backup as a second layer of protection, not your only backup.

What if I do not have an external drive?

Start with a cloud service like OneDrive (free with Windows) or Google Drive (free, works on any computer). Move your important documents and photos into that folder. It is not a complete backup, but it is better than nothing. Buy an external drive when you can afford one, and set up File History or Time Machine to use it.

Do I need to back up my entire computer or just my files?

Backing up just your files (documents, photos, email) is enough for most people. If your hard drive fails, you can reinstall Windows or Mac and restore your files from backup. A System Image or Time Machine backup takes longer to create and restore, but it saves you the time of reinstalling everything. Choose based on how much time you have and how much storage space you have available.

What happens if my backup drive gets infected with malware?

Malware on a backup drive is rare but possible. If it happens, disconnect the drive from the internet when ready and do not plug it into another computer. Restore your main computer from an older backup that you know is clean, or from a cloud backup. You may need to replace the external drive.

How do I know if my backup is working?

Check your backup settings once a month. On Windows, open Settings and go to Backup to see when File History last ran. On Mac, open System Settings and check Time Machine to see the last backup date. Try restoring a single file to make sure the backup actually works — do not wait until you need it to find out it failed. If you see error messages, troubleshoot them right away.