We've all been using computers for a while now and I bet none of us have been spared from at least one data loss related problem in our technical "career". Data is so easily losable that you're practically forced to make backups for everything you have, for obvious safety reasons. Data loss can occur due to several reasons, including:

- Physical damage - when your data storage unit gets physically damaged, data recovery is often difficult. Physical damage can translate into a badly scratched CD or DVD containing essential data, a failing hard disk head or motor and so forth. Physical damage can be avoided, but you can never really protect yourself from it 100%. A hard disk for example, can break down due to aging, constant workload and so forth. CDs and DVDs aren't fully protected even if you keep them in the cleanest, scratch-free conditions possible.

- Logical damage - logical data damage takes place at file structure level as opposed to physical level. Logical damage is more common, as it can be caused by numerous additional factors such as power outages, system crashes, driver problems, RAID controller issues and so forth.

- Human error - human error factors include everything from "oops, I accidentally pressed delete" to overwriting files, moving them around, formatting over essential files and so forth. Basically, of the three types of data loss causes, human error ones are the easiest to avoid and yet they are the most common, because of the users' low computer skills, impatience or forgetfulness.

Sure, if you're a simple user that lost some important data, you won't really be interested in knowing WHY you lost it, but rather if you can get it back. Still, data recovery may often depend on the "WHY you lost it" factor. And unfortunately, in some rare cases, data recovery becomes impossible and the most common of data loss categories is the physical damage one.

If your hard disk blows up on you, there's absolutely nothing to be done about it and no specialized data recovery program or data recovery professional will be able to help you out. But not all hardware (physical) problems fall into this category. For example, a hard disk with a failing motor still holds a chance for data recovery, whereas if the section that holds the logical data gets burnt out or magnetized, you most likely have no chance of getting anything back. Some physical problems may be partially fixed, with only a part of the data being recovered. Although this is never a reason to cheer for, you can at least scavenge up some of your lost data.

The easiest type of data loss to recover is, fortunately, the one falling under the human error category (fortunately - because this is also the most common). When you delete a file from your operating system, it won't show up in the file structure anymore, but that doesn't mean it's gone forever. What the operating system does, is store away that file on a specific sector of your hard disk, where it is held for sake keeping. The only way you can truly delete these files is by overwriting that sector with new data, over and over again. That's why time is an important factor when it comes to data recovery. If you deleted a file yesterday for example, chances are that your system didn't overwrite it with anything else in that "safe closet" on your hard disk. However, if you deleted it last year and subsequently deleted, overwritten and moved files around your hard disk since then, chances are data recovery becomes impossible.