A folder that appears on your laptop and phone feels reassuring. Both devices show the same files, and changes travel between them. That is synchronisation doing its job. The recovery question is different: if an important document disappears or becomes unusable, where is a usable earlier copy, and can you retrieve it without depending on the damaged device?
Start with what would hurt to lose
Make a short inventory before choosing a tool. Include active documents, family photographs, accounting exports, contacts, website files and any application data stored outside your usual documents folder. Mark which items are replaceable downloads and which are unique. A movie you can download again needs a different recovery priority from the only copy of a signed agreement.
For each unique category, write where it lives and who can access it. A small business might discover that invoices are in a cloud application, project work is on a laptop, and client messages are in an email account. One laptop backup does not necessarily cover all three. Inventory prevents a reassuring green status indicator from hiding an uncovered system.
Understand what each copy does
Sync keeps a working collection aligned. Some services also provide deleted-file recovery and version history, but their availability and retention depend on the service, account and configuration. Check the actual terms instead of assuming every earlier version will remain forever. A propagated deletion may be reversible today and unavailable after a retention period expires.
A backup is a copy kept for recovery. It is most useful when it survives the problem that affects your working files. The NCSC recommends identifying important data, protecting online backup accounts and checking that restoration works. Its guidance also advises disconnecting external backup devices when they are not being used, so an infected computer cannot continuously reach them.
Build a practical two-part routine
Consider an example household with a laptop containing current work and several years of photographs. An automatic online copy can cover ordinary changes. A periodic copy to an external drive, stored safely after use, can offer another recovery route. The exact frequency should follow how much recent work you could afford to recreate, rather than an arbitrary calendar rule.
If you create irreplaceable work every day, a monthly copy leaves a large gap. If a folder rarely changes, repeating it hourly adds little value. Write a plain target such as “I can lose one evening of editing, but not a whole week.” Then choose a schedule and retention arrangement that can meet that target with your available connection and storage.
Do not leave both copies in the same bag as the laptop. Theft, damage or a spilled drink can affect everything together. Equally, an online copy protected by the same weak password as several unrelated accounts has its own weakness. Separate the failure paths where practical, and keep recovery information somewhere you can reach if the laptop stops working.
Check recovery before you need it
Pick a harmless file, copy it into the protected folder, and confirm it arrives in the backup. Restore it into a different location, open it and compare the contents. Repeat with a larger file and one older version if version retention matters. A visible filename proves less than a successfully opened document.
Keep a small record of the last successful test, the folders covered and anything excluded. Review it when you change computers, add an account or start using a new application. Backup protection is an ongoing relationship between files, accounts and recovery instructions; the useful result is a copy you can retrieve, understand and use.
Sources and further reading
This original guide was prepared with AI assistance. Examples are illustrative. The edition date is an assigned date in this 2026 catalogue. See our editorial policy and report a correction.