Click here for an article by Bob Rankin entitled "Rubber Bands, Duct Tape, and The Windows Registry."
It's always good to start with a definition. I like to call the Windows registry "a hideously complex ball of string, rubber bands, duct tape and bailing wire that's supposed to keep track of Windows system settings, your hardware configuration, user preferences, file associations, system policies, and installed software." It was intended to be an improvement on the simple text-based INI files that stored Windows configuration settings, but apparently too many pocket protectors were involved in the design.
One advantage of the registry is that it enables each user of a machine to maintain his/her own settings; each user can have a unique theme, speaker volume setting, set of apps, and so on. But the registry can also apply settings to all users, or a group of users specified by the system administrator (e. g., “adults” and “kids”). The registry is one of the most important files on your hard drive. On the downside, this “all eggs in one basket” approach can lead to problems if the registry is damaged or edited incorrectly.
It may be necessary to edit the registry to correct an error or corruption; to add a setting that is not part of the original design; or to prevent some system activity that is undesired. The registry is a very powerful tool, and if it’s used incorrectly, YES, it can wreak havoc on your system. But with a basic understanding of how it works, and some simple precautions, you need not fear.