How to back up your computer
Back up a computer with the 3-2-1 rule: keep three copies of anything important, on two different kinds of storage, with one copy away from your home. In practice that means the computer itself, an external drive running the system's built-in backup tool, and a cloud backup or synced folder. Test a restore once, because a backup you cannot open is not a backup.
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How to do it
- Decide what matters: documents, photos, tax records and anything you made yourself.
- Plug in an external drive at least as large as the computer's drive.
- Turn on the operating system's built-in backup tool and point it at the drive.
- Leave the drive connected, or plug it in every week, so backups keep running.
- Set up a cloud backup or a synced folder for your most important files as the off-site copy.
- Restore one file from each backup to prove it works.
- Unplug the external drive between backups if you can, so ransomware cannot reach it.
Common mistakes
- Treating one external drive as a full backup plan.
- Never testing a restore until the day it is needed.
- Keeping the backup drive next to the laptop in the same bag.
Quick self-check
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Teach this to someone
A one-page sheet for showing a friend, a roommate or a kid: what to say, what to show, and one question to check it landed.
Teach: How to back up your computer
What to say
Back up a computer with the 3-2-1 rule: keep three copies of anything important, on two different kinds of storage, with one copy away from your home. In practice that means the computer itself, an external drive running the system's built-in backup tool, and a cloud backup or synced folder. Test a restore once, because a backup you cannot open is not a backup.
What to show, in order
- Decide what matters: documents, photos, tax records and anything you made yourself.
- Plug in an external drive at least as large as the computer's drive.
- Turn on the operating system's built-in backup tool and point it at the drive.
- Leave the drive connected, or plug it in every week, so backups keep running.
- Set up a cloud backup or a synced folder for your most important files as the off-site copy.
- Restore one file from each backup to prove it works.
- Unplug the external drive between backups if you can, so ransomware cannot reach it.
The check question
Ask: What does the 3-2-1 rule ask for?
Related skills
- How to back up your phone
- How to keep your devices updated
- How to wipe a phone or laptop before selling it
- Every skill in Tech and Digital Safety
Words on this page
Sources
- National cybersecurity agency guidance for home users, 2026. Checked September 28, 2026.
Last reviewed . First published .