Did you know that every hard disk made has a specification called "mean time between failures" or MTBF? ("Mean," if you remember back to grade school, is the same as "average.") In other words, all hard drives fail eventually; it's just a matter of time.

Backup, therefore, is fundamental to maintaining peace of mind when it comes to computing. If you know your documents (and email and photos and other important items) are safely and securely backed up, then any problem with your computer is considerably less stressful.

It's when you have to wonder, "have I lost that file forever?!" That you completely lose your Zen and go screaming to the nearest electronics store to learn of your fate.

With today's cheap external hard drives and "cloud" solutions for backup, there really isn't an excuse to avoid backup. (Not that we all need excuses; the JFP has been going through server glitches in the past week, and we got caught with a backup that was more than a few days old when we hit a snag—and that was on a press day when I was out of town.) If you have no solution at the moment, then you'll have to spend at least a little bit of money, although the cost can be minimal if you're mostly worried about your personal machine.

Before buying software, though, it's smart to take an inventory. The fundamental questions you're asking are (a) how much "near-line" (easily accessible) backup storage do you need and (b) is it time to move some or all of what you're doing to "the cloud"?

Here are some specific things to think about when considering backup options:

1. What are your email backup needs? If you've already got your email in the cloud (with iCloud, Gmail, Yahoo!, or similar programs) then you may get away with backing up less than some other folks need to. If you're like me and you've got 50GB of email stored in Apple Mail from the past 15 years, you might need a more robust hard disk or online solution.

2. What are your document backup needs? Again, if you're in the cloud mostly with Google Docs, Office 365 or something similar, you may not have all that many documents on your computer's internal storage that you need to back up. Or you may have old files that need to be archived somewhere as you plow forward into this brave new day of cloud computing with your new docs online.

3. What are your multimedia backup needs? Photos, audio files and video files take up a ton of room. The more you work in those mediums, the more backup storage space you're going to need. People who use a computer for multimedia will likely need a more sophisticated solution than those who use their computer just for email and spreadsheets.

4. What "special stuff"—games, smartphone sync software, passwords, financial software—do you have that needs to be backed up?

5. Do you have the original disks for applications and operating systems, or would you need to reinstall those from a backup?

6. Do you often create multiple revisions of files that you would like access to, so that you could "restore changes" from an older document, image or similar file?

With this assessment in place, you can get a better sense of your backup needs, particularly the amount of storage you need.

If you're looking at a lot of gigabytes of data that you need quick access to, then a large external hard disk—one or two terabytes are inexpensive these days—might be the right solution. That same hard disk might be handy if you're looking to "clone" your current drive so you have the ability to fully restore in the future.

What software should you use? If you're running Windows 7, you've got Backup and Restore built right in; Macs have Time Machine. Both can be used with external hard drives to create both "system restores" and incremental backups. For Macs, I also like Carbon Copy Cloner (http://www.bombich.com) which is free software for file-by-file cloning of existing folder or drives without requiring a Time Machine setup.

If you have fewer mission-critical files to back up—and you've got the DVDs on hand to re-install applications or your OS—then an online solution might be an alternative. Carbonite (http://www.carbonite.com), Mozy (http://www.mozy.com) and iBackup (http://www.ibackup.com) offer Windows and Mac support for backing up files online. You can generally set the software and forget it; the software works in the background (in some cases, only kicking in when you're idle on your computer) to complete the initial backup of your critical files. Later, scheduled backups are "incremental," meaning they're adding just the files that have been added or changed.

Those set-and-forget services can get expensive for massive storage. In those cases, Arq for Mac (http://www.haystacksoftware.com) can back up directly to Amazon's S3 service, which offers great pricing and high volume levels (hundreds of gigabytes.) JungleDisk (http://www.jungledisk.com) offers Windows or Linux backup to Amazon S3 and similar services for larger installations.

Finally, it's worth considering that even if you have a good backup solution in place, a little "fault tolerance" goes a long way. That's right; two backups, at least on really critical stuff. Sign up for a Google Drive, DropBox or similar online storage drive and drop the files on there that you would need in case of a 100-year flood or alien invasion—particularly stuff you're working on right now. That way, you can access your critical stuff from a friend's computer or public terminal of some kind if the worst sort of computing catastrophe strikes.

JFP and BOOM Jackson Publisher Todd Stauffer has authored or co-authored more than 40 books on technology and computing.