Security

How to Back Up Your Data: The 3-2-1 Rule

Last updated November 6, 2026 · By the PC Guide Info editorial team

Every storage device can fail, and files can be lost to accidents, theft, fire or malicious software. A backup is the only reliable protection.

The 3-2-1 rule

3 copies of your data: the original and two backups.
2 different types of storage, for example your computer and an external drive.
1 copy kept off-site, such as cloud storage or a drive stored elsewhere.

What to back up

Documents, photos, videos, email archives, financial records, browser bookmarks and anything you could not easily replace. Programs can usually be reinstalled, but your personal files cannot.

Backup options on Windows

File History: backs up your personal folders to an external drive.
OneDrive folder backup: syncs Desktop, Documents and Pictures to the cloud.
Third-party tools and other cloud services: many offer automatic, encrypted backup.

Sync is not backup

Cloud sync services mirror changes, including deletions. Choose a service that keeps previous versions, or keep a separate backup, so you can recover from mistakes and ransomware.

Protect against ransomware

Ransomware encrypts your files and demands payment. Keep at least one backup disconnected from your computer, such as an external drive you only plug in during backups, or a cloud service with version history.

Test your backup

Occasionally restore a few files to be sure the backup works. A backup you have never tested is only a hope.

Make it routine

Automatic backups are best. If you back up manually, set a recurring reminder, for example on the first day of each month.

This article is for general information only and is not professional advice. Features, prices and menu names may change between software versions. See our disclaimer.