How to Back Up Your Computer: A Simple 3-2-1 Plan

A backup is a second copy of your files kept somewhere else. Hard disks fail, laptops are lost, and ransomware can lock files. A backup lets you recover your photos, documents and work when something goes wrong. The best-known simple plan is the 3-2-1 rule: three copies of your data, on two different types of storage, with one copy kept away from home.

The 3-2-1 rule

Three copies: your original files and two backups.
Two types of storage: for example an external hard disk and cloud storage.
One off-site copy: a cloud service or a drive kept at another location.

Choose your tools

System	Built-in backup
Windows	File History, or backup in Settings, then Windows Backup
Mac	Time Machine, which needs an external drive

Both systems can back up to an external drive automatically. Connect the drive once a day or week and let the backup run.

Add cloud backup

Cloud storage gives you an off-site copy. Keep your most important folders in a synced service such as OneDrive, Google Drive or iCloud. Check that the service really syncs the folders you care about, because some only sync certain locations.

What to back up

Documents, photos, videos and music you cannot easily replace
Email archives and contacts
Browser bookmarks and important passwords stored in a password manager
Project files and any work from school or the office

You do not usually need to back up installed programs. You can reinstall them from their sources.

Test your backup

A backup you have never restored is a hope, not a plan. Once every few months, open a file from the backup and check that it works. Look at the backup drive to make sure it still has space.

Protect the backup

Keep the external drive disconnected when it is not backing up, so ransomware cannot reach it. Use a strong password on cloud accounts and turn on two-factor authentication, as explained in what two-factor authentication is.

Frequently asked questions

Is cloud backup enough on its own?

It is a good start, but a second local copy helps if your internet connection is slow for large restores.

How often should I back up?

Daily for files you change often, and weekly for everything else. Automated backups make this easy.

Keep one backup offline

Cloud backups are convenient, but an offline copy protects you from accounts that are locked, billing that lapses or a sync error that spreads a deletion. Keep an external drive disconnected most of the time, and reconnect it on a set day to refresh the copy. Store it in a different room or building from your computer if possible.

Write down what you backed up

A short note listing the folders backed up, the drive used and the date saves time when you need to restore. It also helps you spot missing folders. Update the note when you add a new project or change drives.