Only, perhaps, the most important term in all of computing.
Backup is one of those terms we all take for granted — yet it’s not uncommon to find different people who have different ideas of exactly what it means.
It’s so important and so basic to safely protecting your information and your work that it’s worth a little dedicated attention.
Honestly, I’m surprised it’s taken me this long. 1
Become a Patron of Ask Leo! and go ad-free!
Just What Is a Backup?
A backup of something is a copy placed somewhere else. The further that “somewhere else” is from the original, the better protected both are. More copies, in more locations, protects even more.
A backup is a copy
The fundamental concept of a backup is very simple: it’s nothing more than a copy.
A backup is just a copy: of a file, of your data, of a computer, of an operating system, of anything or everything.
Remember this phrase:
If it’s only in one place, it’s not backed up.
By that I mean if you have only one copy of something — call it the original — and something happens to it, it’s gone forever. If a hardware failure, malware, account hack, or similar scenario takes away that one and only original copy, it’s gone.
That’s why I harp so much on backing up.
And backing up is nothing more than making a copy of something.
A backup is a copy somewhere else
Now, for bonus points, let’s talk about the copy’s location.
When we back up, we make a copy somewhere else.
“Somewhere else” is open to interpretation, depending on what you’re doing, but the important thing is that if you make a copy of something, you’re backed up, and the farther that copy is from the original, the better protected it is.
For example, if you’re working on a Word document, you might:
- Click on Save.
- Click on Save As and save the file with another name.
- Copy the document in Windows File Explorer.
Those kinds of actions protect against certain types of failures. Saving periodically as you work protects you from the application crashing by writing your work so far to disk. Save As, or using Windows File Explorer to copy the file, will protect you from changes you later regret by saving a copy of your work before those changes.
They’re not necessarily going to protect you from things like hard disk failure or malware. Moving your backup farther away from the original protects you from more and more things.
- Storing it on an external drive might protect you from a variety of hardware and software failures on your computer.
- Storing it on an external drive you then disconnect and keep in your desk drawer would protect you from all that plus overly aggressive malware.
- Storing it online, or on a disk in a bank vault, would protect you from all that and more, including your house burning to the ground.
Each is conceptually (and often physically) a little “farther away” from the previous location.
When in doubt, more is better
There’s no such thing as too many backups, in my opinion. However, there’s definitely such a thing as too few.
A great place to start is the “rule of three” or “3-2-1 rule”:
- Three copies
- On (at least) two different media types
- With one stored elsewhere
This protects you from multiple types of failures in multiple places.
It’s a great rule with which to start.
And finally, one little clarification:
Is it backup or back up?
This is something that my editor catches me doing incorrectly frequently.
Backup is a noun or an adjective. A backup is a thing. I have a backup or a backup copy or a backup of my hard disk.
Back up is a verb. To back up is an action. I make a backup (thing) by backing up (action).
So a backup is the thing you’re trying to create, and backing up is what I’m trying to encourage you to do!
Subscribe to Confident Computing! Less frustration and more confidence, solutions, answers, and tips in your inbox every week.
I'll see you there!
Footnotes & References
1: Technically, it hasn’t. This article is based on a chapter from a book I published some years ago.