Think about the files on your computer and phone that you would be most devastated to lose. Family photographs spanning decades. Financial records. Important work documents. Creative projects you have invested hours or years into. Tax records. Personal writing. The sum of your digital life.
Now consider that a single ransomware attack, a hard drive failure (which can happen suddenly and without warning, even to drives that seem to be working perfectly), a stolen laptop, a house fire, or a simple accidental deletion can remove all of it in an instant. No warning. No second chance. Permanently gone unless you have a backup.
A proper backup strategy takes about an hour to set up and then runs automatically without you thinking about it. This is the most practical insurance you can buy for your digital life, and most of it is free.
The 3-2-1 backup rule explained
The 3-2-1 rule is the industry standard framework for data protection, and it is the right structure for home users as much as for businesses. The principle: keep 3 copies of your important data, stored on at least 2 different types of media, with at least 1 copy in a different physical location from the others.
Why three copies? Because backups fail. External hard drives fail. Cloud storage accounts can be accidentally deleted. Having three independent copies means that two simultaneous failures are required to lose your data — dramatically less likely than one failure.
Why two different types of media? Because failure modes differ. A ransomware attack might encrypt your computer and any connected external drives. A fire might destroy your computer and external drive stored at home. Cloud storage might become inaccessible if your account is compromised. By using different media types, you ensure that a single catastrophic event cannot destroy all copies simultaneously.
Why one offsite copy? Because localised disasters — fire, flood, theft — affect everything in one physical location. An offsite or cloud backup is immune to local physical events.
Cloud backup: the offsite copy that runs itself
Cloud backup is the most practical way for most people to maintain an offsite copy, and many cloud services are either free or very low cost. The best options depending on your devices:
Apple iCloud is the default for iPhone, iPad, and Mac users. For iPhone and iPad, iCloud Backup automatically backs up your device over Wi-Fi when plugged in and the screen is locked — capturing everything including app data, messages, photos, and settings. Enable it at Settings → your name → iCloud → iCloud Backup → Back Up This iPhone. For Mac, iCloud Drive can sync your Desktop and Documents folders automatically. The free tier provides 5GB, which is quickly filled — 50GB for £0.99/month or 200GB for £2.99/month are the most practical options.
Google One provides backup for Android phones (Settings → System → Backup → Google Backup) and can sync Google Drive files across devices. 15GB is free, 100GB is £1.59/month.
OneDrive integrates deeply with Windows 11 and Microsoft 365. Files saved to your OneDrive folder are automatically synced to the cloud. Free tier provides 5GB; Microsoft 365 Personal (£60/year) includes 1TB of OneDrive storage plus the full Office suite.
Backblaze is the choice of security professionals for comprehensive computer backup. It backs up everything on your computer — not just a synced folder — for around £7/month with no storage limit. The set-it-and-forget-it simplicity and the comprehensive coverage make it excellent value for anyone with substantial data to protect.
External hard drive backup: the local copy
An external hard drive provides a fast, local backup that does not depend on internet connectivity and allows rapid file recovery. A 1TB or 2TB external USB drive costs between £40 and £80 and will last many years with normal use.
On Mac, Time Machine is the built-in backup system. Connect an external drive, open System Preferences → Time Machine, and select your drive as the backup destination. Time Machine automatically takes hourly backups of the past 24 hours, daily backups for the past month, and weekly backups until the drive is full. It runs invisibly in the background whenever the drive is connected.
On Windows, use File History: Settings → Update & Security → Backup → Add a Drive, select your external drive. Windows will automatically back up your Documents, Desktop, Downloads, Pictures, Music, and Videos folders hourly by default. You can add additional folders to include anything stored elsewhere.
What specifically to make sure is backed up
- Personal photographs and videos — irreplaceable family memories, often the most emotionally significant data
- Financial documents — bank statements, tax returns, receipts, invoices
- Work documents — project files, client records, anything with professional significance
- Creative work — writing, music, design files, programming projects, video editing projects
- Your password manager vault export — though your password manager syncs this for you automatically
- Emails, if you use a desktop email client that stores messages locally rather than on the server
- Browser bookmarks and saved data
Testing your backups: the step everyone skips
A backup you have never tested is a backup of unknown reliability. Backup systems fail silently — the process completes without errors but the restored files turn out to be corrupted, incomplete, or inaccessible. You do not want to discover this when you are desperately trying to recover from a ransomware attack or a failed hard drive.
At least every three months, restore a small sample of files from each of your backup systems to verify they work correctly. Pick five or ten files — a few photos, a document, a video — and try restoring them to a different folder on your computer. Open each one and confirm they are intact. This process takes about five minutes and confirms that your backup system is actually working.