One key for everything doesn't make a lot of security sense, so why do we do it for online passwords?
Your username and password works as an online identity, and there's a lot of harm that can be done if yours is no longer your own.
We're not sure how big the problem is, but estimates of the impact of cybercrime on Australia's economy range from $1 to $17 billion a year.
Considering how often we're forced to use them, it's tempting to use the same password for more than one site.
But if something were to go wrong, you don't want the loss of one key to mean replacing every lock.
Use one unique password for each account, and you'll be safer and more secure as a result.
This article was originally published in the Canberra Chronicle on Tuesday, 11 October 2016.