Hard drives fail, laptops get stolen, spilled coffee happens, and ransomware locks files without warning. Most people only think about backups after something goes wrong, and by then it is usually too late. The good news is that a solid backup setup for a Windows PC or a Mac is simple, cheap and mostly automatic once you set it up. This guide explains the 3-2-1 rule, the options available and a routine you can actually stick to.
Why a single copy is not a backup
Files that live only on your computer are one accident away from being lost. Even a copy on a second folder of the same drive does not help if the drive itself dies. A real backup is a separate copy, stored somewhere that would survive whatever damaged the original. That might be a fault, theft, fire, a virus or a simple deletion mistake.
Syncing is not the same as backing up either. Services that mirror a folder across devices will faithfully mirror a deletion or an encrypted ransomware file too. Many cloud services offer version history or a recycle bin that can help, but you should not rely on those alone.
The 3-2-1 rule
A widely used guideline among IT professionals, and mentioned in guidance from bodies such as the US Cybersecurity and Infrastructure Security Agency, is the 3-2-1 rule. Keep three copies of your important data: the original plus two backups. Store them on two different types of storage, for example your computer’s internal drive and an external drive. Keep one copy off-site, such as in cloud storage or an external drive kept at a relative’s home.
For most households that means: your computer, an external hard drive or SSD at home, and an online backup or cloud storage account. You do not need anything complicated to meet the rule.
Option 1: An external drive
An external hard drive or SSD is the cheapest and fastest place to start. Capacity matters: choose a drive at least as large as the data you want to protect, and ideally two to three times larger so it can hold several versions over time. Plug it in, then let your system’s built-in tool do the work.
On Windows 11, the Windows Backup app and File History can copy folders to an external drive, and recent versions can also back up settings and folders to a Microsoft account, subject to the storage on your plan. On a Mac, Time Machine is built in: connect a drive, choose it in System Settings, and it saves hourly snapshots and lets you step back to earlier versions of files.
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The weakness of an external drive is that it sits next to your computer. A fire, flood or burglary could take both, and ransomware can sometimes encrypt a drive that stays plugged in. Unplug it when you are not backing up if you can, or rotate between two drives.
Option 2: Cloud storage and online backup
Cloud services give you the off-site copy. Options include general storage such as OneDrive, iCloud and Google Drive, and dedicated backup services that copy your whole computer in the background. General storage is simpler and good for documents and photos; dedicated backup suits people with large amounts of data who want everything covered. Check the price per year, the storage limit, how long deleted files are kept and whether data is encrypted.
Remember that free tiers are small, so a typical photo and video library will often need a paid plan. If you are already running low on space, our guide to freeing up space on a Windows laptop can help you decide what is worth backing up in the first place. Phone photos are a separate job, covered in our article on backing up phone photos.
What to back up first
You do not have to copy everything. Prioritise the things you cannot replace: family photos and videos, documents, tax and financial records, work files and any creative projects. Programs and the operating system can be reinstalled, so they matter less, although a full system image can save hours of setup if your drive fails.
Do not forget data held elsewhere, like browser bookmarks, email archives, and recovery codes for your accounts. If you use a password manager, make sure you know how to get back into it; our piece on password managers explained covers recovery options.
Make it automatic and test it
A backup you have to remember is a backup that will eventually be skipped. Turn on scheduled backups so they run in the background, and leave the external drive connected at set times, or use a network drive if you are comfortable with the setup. Check once a month that the latest backup actually completed.
The step most people skip is testing. Once or twice a year, try restoring a few files to a different folder. If you can open them, your system works. If you cannot, you have found the problem while it is still harmless.
Protect your backups
Backups often hold your most sensitive files in one place, so protect them. Encrypt external drives where your system allows, using BitLocker on Windows editions that include it or the encryption option in Time Machine on a Mac. Protect your cloud account with a strong unique password and two-step verification; our guide to two-factor authentication shows how. Keep at least one backup disconnected from the computer so ransomware cannot reach it.
A simple routine to copy
Here is a realistic setup: keep your important folders synced to a cloud service for the off-site copy, run Time Machine or File History to an external drive for the local copy, and spend ten minutes at the start of each month checking both are working. Add a test restore each spring and autumn. That covers the 3-2-1 rule without much effort.
This article is general information rather than professional IT advice. Features and prices change, so check each provider’s current details before you commit. The most important step is the first one: set up a backup today, because the best time was before your drive failed.
