What backing up means and why it matters

A backup is a copy of your files stored somewhere separate from your computer. If your hard drive fails, you get hacked, your device is stolen, or malware wipes your data, a backup lets you restore everything—your photos, documents, email, and settings—to a new or repaired machine. Without one, that data is often gone for good.

Most people think a backup is something that happens automatically or costs money. It doesn't have to be either. You can set up a backup in under an hour using tools already built into Windows or Mac, or using free services like Google Drive or Dropbox. The key is choosing a method that fits how you work and then actually turning it on.

Key Takeaways

  • Windows includes File History and Mac includes Time Machine—both built-in tools that automatically back up your files to an external drive once you plug it in.
  • Cloud backup (Google Drive, OneDrive, Dropbox) stores copies online so you can recover files even if your computer is stolen or destroyed.
  • The safest approach combines both: an external drive for fast local backups and cloud storage for protection against physical loss.
  • Set up automatic backups once, then check every few months that they are actually running—many people turn on a backup and forget it stops working.

Using an external drive with Windows File History

Windows File History is the simplest backup method if you have a Windows computer. It automatically saves copies of your files to an external drive (a USB hard drive or external SSD) every hour, keeping versions from different dates so you can restore an older version if you need it.

To set it up: plug in an external drive, open Settings, search for "File History," and click "Turn on." Windows will use that drive from then on. Every time you plug it in, File History backs up any files that changed since the last backup. You don't have to do anything else.

The catch is that File History only works when the drive is plugged in. If your computer is stolen or your house floods, the external drive might be gone too. That's why pairing it with cloud backup is smart—one protects against hardware failure, the other against physical loss.

Using an external drive with Mac Time Machine

Mac's Time Machine works the same way as Windows File History. Plug in an external drive, go to System Settings > General > Time Machine, click "Add Backup Disk," and select your drive. Time Machine then backs up automatically every hour.

Like File History, Time Machine only backs up when the drive is connected. If you want continuous protection, leave the drive plugged in. If you want to back up on a schedule (say, once a week), plug it in when you're ready and Time Machine will catch up with everything that changed.

One useful feature: Time Machine keeps backups going back weeks or months, so if you accidentally delete a file and don't notice for a while, you can still recover it from an older backup.

Cloud backup with Google Drive, OneDrive, or Dropbox

Cloud backup stores your files on a company's servers instead of a physical drive in your home. The advantage is that your files are safe even if your computer, your external drive, and your house all disappear. The disadvantage is that you're trusting a company with your data, and you need an internet connection to restore large amounts of files.

Google Drive gives you 15 GB free and works on Windows and Mac. Install it on your computer, and it syncs selected folders to Google's servers automatically. You can access those files from any device by logging into Google Drive online.

OneDrive (Microsoft's service) also offers 5 GB free on Windows and Mac. It works the same way—install it, pick folders to sync, and your files are backed up to Microsoft's servers.

Dropbox provides 2 GB free and works similarly. All three let you restore individual files or your entire backup if something goes wrong.

The free tiers are usually enough for documents and photos. If you have a lot of video or large files, you'll hit the limit and need to pay for more storage—typically $2 to $10 per month depending on how much space you need.

Combining local and cloud backup for full protection

The best backup strategy uses both methods. An external drive backs up your entire computer quickly and lets you restore everything in minutes if your hard drive fails. Cloud backup protects against theft, fire, or flood—disasters that would destroy both your computer and an external drive in the same location.

A practical setup: use File History or Time Machine to back up to an external drive you keep at home, and use Google Drive or OneDrive to sync your most important folders (Documents, Photos, Desktop) to the cloud. Your everyday files are protected both ways, and your full computer is protected locally.

If you have limited cloud storage, prioritize photos and documents over applications and system files—those can be reinstalled, but your personal files cannot.

Checking that your backup is actually working

Many people set up a backup and assume it's running. Then months later they discover it stopped working weeks ago—the external drive disconnected, the cloud service hit its storage limit, or a software update broke the connection.

Every month or two, verify your backup is current. For an external drive, plug it in and check the backup software (File History or Time Machine) to see when the last backup completed. For cloud backup, log into the service online and confirm that today's date or yesterday's date appears next to your files.

If the last backup is older than a week, something is wrong. Check that the external drive is plugged in, that you're logged into your cloud account, and that you have enough storage space. If you're still stuck, search for the specific error message—most common backup problems have straightforward fixes.

What to back up and what you can skip

Back up your Documents, Desktop, Downloads, Photos, Music, and Videos folders—these contain the files you created and can't replace. Also back up your email if your email client stores messages locally (Gmail and Outlook online don't need local backup because they're already in the cloud).

You don't need to back up installed applications. If your computer fails, you can read and reinstall them. Backing up the entire system folder is overkill for most people and wastes storage space.

If you use specialized software (design tools, music production, accounting software), check whether it stores project files in a standard folder. If it does, make sure that folder is included in your backup. If it stores files in a hidden location, you may need to back up that location separately.

Frequently Asked Questions

How much storage do I need for an external backup drive?

A good rule: get a drive at least as large as your computer's hard drive, ideally larger. If your computer has a 500 GB drive, a 1 TB external drive gives you room for multiple backup versions. External drives are cheap—a 2 TB drive costs $50 to $100 and lasts years.

Is cloud backup safe? Can the company see my files?

Major services like Google, Microsoft, and Dropbox encrypt your files so that even their employees cannot read them. Your files are safer in their data centers than on a single external drive in your home. The real risk is your password—use a strong, unique password and enable two-factor authentication if the service offers it.

What if I run out of cloud storage?

Stop syncing new files until you delete old ones or pay for more storage. Your existing backup stays safe—you just can't add new files. You can also choose to sync only certain folders instead of everything, which uses less space.

Can I back up to a drive I keep at a friend's house?

Yes. An external drive at a different location protects against local disasters. Plug it in when you visit, let the backup run, and take it back with you. This is less convenient than cloud backup but costs nothing and keeps your data completely offline.

What happens if I restore from a backup and I've already deleted files I want to keep?

If you restore your entire computer from a backup, you go back to how it was at that backup date—any files you deleted after that date are gone. If you restore individual files, you can pick and choose which ones to recover, so deleted files come back but everything else stays current.