What backing up means and why it matters

A backup is a copy of your files stored somewhere other than your computer's main hard drive. If your drive fails, gets infected with ransomware, or your laptop is stolen, the original files are gone—but your backup survives. Without a backup, you lose photos, documents, financial records, and anything else you haven't printed or written down elsewhere.

Most people wait until disaster strikes to think about backups. By then it's too late. The good news is that backing up takes a few hours to set up once, then runs automatically in the background. You don't have to think about it again.

Key Takeaways

  • A backup is a complete copy of your files stored on an external drive, cloud service, or both—separate from your computer.
  • The three main backup methods are external hard drives, cloud storage services, and built-in backup tools like Windows Backup or Mac Time Machine.
  • The best approach uses two backups: one external drive at home and one cloud service, so you're protected against theft, hardware failure, and data corruption.
  • Set up automatic backups so files copy without you having to remember to plug anything in or log in manually.
  • Test your backup by restoring a file from it before you need it in an emergency.

External hard drives: the simplest physical backup

An external hard drive is a portable storage device you plug into your computer via USB. It holds a complete copy of your files. When you unplug it and store it in a drawer or safe, that copy stays safe even if your computer is destroyed.

To set up an external drive backup on Windows, plug in the drive, open Settings, go to System > Backup, and select "Backup using File History." Choose the external drive as your destination and turn on automatic backups. Windows will copy new and changed files every hour by default. On a Mac, open System Settings, go to General > Time Machine, click "Add Backup Disk," select your external drive, and toggle Time Machine on. Your Mac will back up automatically every hour.

External drives cost between $50 and $150 depending on storage size. A 1 or 2 terabyte drive is enough for most people. The downside is that the drive can fail, get lost, or be destroyed in the same disaster that damages your computer—so an external drive alone is not a complete solution.

Cloud backup services: protection against physical loss

Cloud backup stores your files on servers owned by a company like Microsoft, Apple, Google, or Backblaze. Your files live on the internet, not in your home, so they survive theft, fire, flood, and hardware failure. You can also access them from any device with an internet connection.

Microsoft OneDrive (built into Windows), Apple iCloud (built into macOS), and Google Drive are free or low-cost options that sync your files automatically. They work best for documents, photos, and smaller files. For a complete computer backup including system files and programs, Backblaze is a dedicated service that costs about $7 per month and backs up everything on your computer continuously. Carbonite and IDrive are similar alternatives.

The trade-off with cloud backup is that it depends on your internet connection. If your upload speed is slow, the first backup can take days or weeks. Cloud services also store your files on someone else's servers, so consider whether you're comfortable with that for sensitive documents. Most reputable services encrypt your files so the company cannot read them.

Combining external and cloud backups for full protection

The safest approach uses both methods. An external drive at home gives you fast, local access to restore files. A cloud backup protects you if your home is damaged or your external drive fails. Together, they cover almost every disaster scenario.

Set up your external drive first using File History (Windows) or Time Machine (Mac). Then sign up for a cloud service—OneDrive, iCloud, or Google Drive for documents and photos, or Backblaze for a complete system backup. Turn on automatic syncing or backup for both. After a few hours of initial copying, both will run in the background without any action from you.

This two-backup method costs little: an external drive is a one-time $50–$150 purchase, and cloud backup is free to $10 per month depending on what you choose. The cost is far less than paying a data recovery service if your computer fails.

How to test your backup before you need it

A backup that has never been tested is just a hope. Before you rely on it, restore a file from it to make sure it actually works. Pick an unimportant file—a photo, a document you don't need—and practice restoring it.

On Windows with File History, right-click a folder, select "Restore previous versions," and choose a backup date. On Mac with Time Machine, click the Time Machine icon in the menu bar and select "Enter Time Machine," then browse to an old version of a file and restore it. If you use cloud backup, read a file from the cloud service to a different folder on your computer. If all three methods work, your backups are real.

What to back up and what you can skip

Back up everything in your Documents, Pictures, Desktop, and Downloads folders. Back up any folder where you store financial records, medical information, or work files. Back up your browser bookmarks and passwords (most password managers sync automatically to the cloud).

You do not need to back up your operating system or installed programs if you use a cloud backup service like Backblaze that captures everything, or if you keep your original installation media. If your drive fails completely, you can reinstall Windows or macOS from a recovery disk and then restore your files from the backup. This takes a few hours but costs nothing.

Skip backing up temporary files, cache, and the Recycle Bin or Trash folder. These are junk and will only slow down your backup.

Backing up a laptop or computer you use away from home

If you travel or work from different locations, an external drive is less practical because you have to remember to carry it. Cloud backup is the better choice. Services like Backblaze, OneDrive, iCloud, and Google Drive back up automatically whenever your computer is connected to the internet, whether you're at home, at a coffee shop, or at an office.

If you do use an external drive, keep it in a safe place at home and plug it in once a week when you return. The backup will catch up on all the files you changed while you were away. For maximum safety with a laptop, use both: cloud backup for continuous protection while traveling, and an external drive for fast local restores when you're home.

Frequently Asked Questions

How long does a first backup take?

An external drive backup of a typical computer takes 2 to 8 hours depending on how much data you have and how fast your USB connection is. Cloud backup takes longer—often several days or a week for the first upload if you have hundreds of gigabytes of files and a slow internet connection. After the first backup, only new and changed files are copied, so updates are much faster.

Can I back up to a USB flash drive instead of an external hard drive?

USB flash drives are too small and too slow for regular backups. They typically hold 32 to 256 gigabytes, which is not enough for most computers. Use an external hard drive or cloud backup instead.

What if I don't have enough space on my external drive for a complete backup?

Buy a larger external drive. A 2 or 4 terabyte drive costs $60 to $100 and will hold backups of most computers. Alternatively, use cloud backup, which has unlimited storage for a monthly fee, or back up only your most important folders to the external drive and use cloud backup for everything else.

Do I need to back up if I use cloud storage like Google Drive or OneDrive?

Cloud storage and cloud backup are not the same. Google Drive and OneDrive sync files you choose to store in them, but they don't automatically back up your entire computer. Use them alongside an external drive or a dedicated backup service like Backblaze for complete protection.

What happens if the backup service goes out of business?

If a cloud backup company closes, it usually gives customers weeks or months to read their files before shutting down. To be safe, keep an external drive backup as well. That way you're not dependent on any single company.