Now, we are done with the hows and have a good handle on the whys.
Now we move onto the whats (you can do with your backups). True, they can save you in case of disaster, but I use my backups for more than just disaster recovery.
I guess, part of this will be a how to, but not really. I will burn the backups onto CD from time to time but I only do this on super critical sites and rapidly changing sites. I often times burn multiple CDs and give one copy to the client and stash the other in a fireproof safe. Certainly, when a website gets decommissioned I back it up, burn it, and stash it. Then when, I need to show someone else the website for sales purposes then I have a copy I can quickly restore the site.
First, some terminology. What do I mean by production, test, and development? By production I mean the main website that everyone on the Internet can view. You do not make your changes to the production site unless you are confident the changes will work as you expect. The goal here is for zero boo-boos on your production site. The development site is the complete opposite of your production site.
Your development site should not be accessible by the public (in fact if it is on your laptop or desktop shielded from the Internet that is quite fine). In an ideal world, this is where all of your changes are initially made. If your changes do not work, the site the world sees is unaffected. You can work without fear of destroying your live website. the test website is a combination of your production and development site.
I make the changes to the site on my laptop (development) and when I believe the changes are proper I will move the changes to the test site. Then I ask concerned users or my client to review the test site, once they approve of the changes, then I implement those changes on the production website. Guess what, this elaborate process does not guarantee your changes will work on the production system, but the incidence of failure will be greatly reduced.
One major use of my backup sets is to replicate the site for test and development purposes. This is not so straight-forward as a simple site restoration. Most likely (especially if you use WordPress) there will be database entries with your domain. If you are moving the site to a different domain (as I frequently do when setting up test and development sites) you must search for and replace the production domain to the new test or development domain. Most text editors can do this search and replace