This is my reply:
Well, I never backup to only ONE place! Having only one backup is almost as dangerous as having none. I always make at least three backups of my desktop system and store them in at least three different locations. I probably backup more than that on the two laptop computers I use (Windows and Macintosh).
I back up everything on my desktop computer's hard drive to an external hard drive that sits beside the computer. I use TimeMachine software for that, a great backup program that is included with every Macintosh. That's the fastest backup I have and it works automatically all day and night, making backups of all new files automatically within minutes after I create them. I never have to remember to make backups as TimeMachine does all that automatically.
If I need to later retrieve a file, using that full backup of everything on a hard drive attached directly to the computer will be the fastest way to restore it. It even saves all versions of all files. If I need to retrieve a file version as it existed last month or last year, I can do that within seconds using Time Machine and that external hard drive. HOWEVER, I also know that a fire, flood, hurricane, tornado, or even a burst water pipe might damage or destroy my house, my computer, AND that hard drive that sits beside my computer. Storing backups only in the house is high risk. Therefore, I also make off-site backups.
I have experimented with all sorts of online backup services. I now back up all of my documents, family photos, and much more to Amazon S3 and Amazon Glacier. I don't back up the operating system or the programs. After all, I can always get new operating systems and new programs. All I back up off-site is the important things: my pictures, my documents, and the other things I created. I like Amazon's backup services ( S3 and Glacier) but am reluctant to recommend them for others. They are quite difficult to get set up and working if you haven't spent your life supporting computer systems of all sorts of operating systems, as I have. However, I struggled through it and it works well for me now. Best of all, it automatically backs things up while I am sleeping. Maybe I'll write an article someday: "The Easy Way to Perform Backups to Amazon S3 and Amazon Glacier." All I have to do is first figure out what the easy way is.
For most other people, I would recommend Mozy or BackBlaze or CrashPlan or Carbonite or any of the other dozen or so online backup services. They are easier to set up than is Amazon S3 or Amazon Glacier although they cost more than Amazon S3 and a lot more than Amazon Glacier.
Next, I make copies of all my documents to Dropbox. I don't do that so much for backup purposes but more for the convenience that Dropbox offers. Dropbox automatically copies files to and from the desktop computer, as well as to and from the laptops. The same files also become available on request in the handheld cell phone, and any other place I specify. When I turn the laptop on, all my new Dropbox files are immediately copied to the laptop and are available there within a minute or two; I never have to manually copy them. I stopped using the /Documents folder on my hard drive (Windows used to call it \My Documents.) Instead, I moved all those files from /Documents to /Dropbox and all new documents I create are now saved in /Dropbox. The /Documents folders on my computers are empty.
My 20,000+ .mp3 music files are on my computer's hard drive and also are backed up on the external hard drive beside the computer as well as copied onto an iPod music player and to a hard drive attached to the hi-fi in the living room.
I often copy various files to flash drives which I keep in my backpack/briefcase although that's a manual process and I don't keep everything there. Just my Powerpoint presentations, all my genealogy data, a lot of recent photographs I have taken, and a few other things that I might need at any time when I meet a friend or relative.
For instance, I took several dozen pictures and videos last night at a party celebrating a relative's high school graduation. While those are already backed up on my external hard drive and on Amazon Glacier, I also keep copies on flash drives in my pocket or backpack. If I meet another relative who would like copies of everything, I can quickly insert the flash drive into his or her computer and copy the several gigabytes of files over. (Those videos are large!) That's easier and cheaper than using CD-ROM disks and it works as additional backups for me.
So, yeah, I think I am backed up. But I change backup procedures frequently as I experiment with new things. My only rule is: "You can never have too many backups!"