Most computers users are generally not afraid to defragment their hard drives, delete temporary files or even reinstall Windows to their computer. But mention editing the registry and even some well-seasoned geeks may break out in a cold sweat and defer that task to someone more qualified.

The Windows registry is a database that references all that happens in a computer including all hardware, software, the operating system and its users. It is a central repository for the system that stores all the instructions required by the computer to function. It maintains all settings and options.

When you click an icon, it's the registry that decides what to do from there.

It is organized like the Windows file structure. The operating system has folders and files, while the registry has keys and values. They are both set up in a hierarchical format, each file/value being subservient to the folder/key above it.

There are five main keys (called HKEYS), each controlling specific areas of your computer.

You can alter the registry, directly or indirectly, by making any changes to your system.

Suppose you decide to change your desktop image. You can do it manually from the desktop, from the control panel or from the registry. By making changes from the first two locations, ultimately the adjustments are reflected in the registry.

You need to tread lightly though, as a few misplaced clicks of the mouse in the registry and the well-honed, expensive computer you so cherish is turned into a doorstop.

You could go through the life of a computer never cleaning the registry, but eventually it will begin to slow down. When applications are deleted from a system, the programs are deleted, but references to them remain in the registry. The same holds true for old shortcuts, fonts and previous users.

The registry can be edited manually using Regedit, a part of Windows, or with a dedicated registry tool. If you do it yourself, I must warn you though: There is no verification after an edit. There are no "Save" or "Undo" buttons. Once a change is made, there is no turning back. The best advice I can give is to back up the registry if you plan to alter it.

System Restore is the most basic way to accomplish this task, but it backs up more than the registry. Also random restore points may be deleted at any time by the system. So although it is an easy method, it's not the best for this purpose.

There are dedicated registry utilities that you can download for free. Some are simply cleaners while others allow you to make adjustments to menu speed, icon size, color schemes, system sounds, wallpaper, screensaver, your right-click options and more. Some utilities can replace your lost Recycle Bin, toggle off that annoying permissions box that always appears or change your password. All of the utilities will offer to make a back-up for you. Take advantage of the offer.

Should you want to back up the registry manually, run Regedit by typing it in the Run Command (XP) or Search box (Vista or Win 7) and hit "Enter." Click on "Computer" above the list of keys. Then click on "File" and then "Export." Be sure to choose a secure destination like a flash drive for the backup. You should save it off of the hard drive so you can access it when you can't access the hard drive.

Editing the registry manually is not difficult; you need only to be careful. You can use the "Find" feature at the top of the Regedit page to look for what you want to adjust. Values are either "0" or "1" and represent either yes or no, or on or off, depending on what it is you're going to change.

You could always Google what you are trying to modify. If you want to auto-hide the task bar in Windows 7, for example and can't find that registry key, Google it. You'll find step-by-step instructions.

Many registry cleaners and optimizers find more errors than others. They are simply more aggressive in their scans. But they also warn you prior to deletion, asking for confirmation. If you aren't sure if a value should be deleted or not, use a less aggressive utility.

Some of the many free registry tools on the Internet that I've found easy to use, are Advanced System Care, Ccleaner, Easy Cleaner and Glary Utilities. These incorporate other useful tools as well. Another, ERUNT is strictly a back-up tool.

If Windows is a mess, before you delve into the registry, first try a reboot, then try Safe Mode (tap F8 at boot) and initiate a System Restore (this is what it was made for) or choose Last Known Good Configuration (also from F8).

You only want to use a registry backup when you have been making adjustments to it and something went awry.

So fear not, geeks and non-geeks alike. The registry is there for us to fine-tune our systems. Just beware the one big caveat — back up before you tune up.

Arthur Glazer is a freelance writer and computer technician in Gainesville. His column appears biweekly on the Business page and on gainesvilletimes.com.