Nothing but a database. It is a very important database to the Windows Operating System where information is kept about

• the software installed on your PC,
• what program should be used to open certain files (file associations),
• user specific settings,
• system hardware drivers,
• operating system settings,
• software settings,
• and more...

To call the registry vital in my view is not appropriate, as there are many applications that run well without being “registered” or actually a part of the registry.

A long time ago, when PC's still were carved out of marble and flint and run by a so called “operating system” (DOS), each installed application kept its settings in a more or less standardized “ini”-file – or something similar to it. Those ini files were kept in the program’s home folder, one or even more for one single program, scattered all over the place. Some of the more system wide settings were kept in two small files (autoexec.bat, config.sys), and Windows 3.1 (and 3.11) introduced the system.ini, the win.ini, reg.dat, system.dat plus the user.dat.

The registry is born. Its files are now stored in the Windows directory and a user.dat is kept in the profile’s folder of the users. This is the official end of splattered entries all over your hard disk.

Windows 95 and the following Operating Systems (NT, 2K, ME) always load the complete registry into memory, regardless of the programs currently active and used. Thus both loading the file into memory and keeping it there was (is) heavy on resources – i.e. boot up speed and memory usage. Considering the less performing hardware of the time, it is easy to understand why keeping your registry clean and tidy was one more thing to do to enjoy a fast(er) machine.

The registry is still there, but memory management has significantly improved. Now, only those parts of the registry that are actually and presently needed are loaded into memory, cleaning the registry will not have much impact on your system performance.

Many activities on our PCs like installing software create entries (keys) in this data base called the “Registry”, sometimes in the thousands. Your software will use these keys to keep settings, default folders and associate file types etc. When you no longer use this software and uninstall it, usually all, some or a few of those keys may be left behind and now point right into the middle of nowhere. These are so called “orphaned keys”, as the information they provide is no longer useful to your system since you uninstalled the software. They occupy a bit of disk space – that’s it. A “registry cleaner” will now try to find the keys that are no longer needed and offer to delete them for you, “in order to improve system performance and stability”.

Well, the point is you probably cannot make an informed decision on what keys are needed and what keys are obsolete. If you have a couple of registry cleaner analyze your system, you will most likely get a couple of recommendations. Some will find fewer keys than others or recommend a different set of keys for deletion. This behavior depends on “aggressiveness” vs. “safety”, the first claiming a thorough sweep, the latter leaving quite a bunch of keys just to "be on the safe side".

Now, consider the following. Your registry is full of old, unnecessary entries occupying a bit of disk space. Amongst those 356 obsolete entries is one that is reported falsely by your registry cleaner, which you will not discover unless you check each and every entry, and of course you need this special piece of knowledge to make the decision.

But you authorize the deletion and the now ensuing calamity caused by the removal of this one really needed key outweigh by far the nonexistent benefit you do not get from cleaning the registry.

Those entries that registry cleaners profess to take care of, that supposedly slow down your system and take up your entire RAM are simply ignored by the memory management of XP and Vista. For one, they are not loaded into memory, and second, even if they were, the size of a single key is so small, it wouldn’t mean a thing in modern RAM of two Gigabytes and more.

Another argument equally lost is the waste of precious disk space. My first machine had the ginormous amount of 5 MB external disk space, but when today you buy a decent home PC it will come with a disk space of 500 Gigabyte and more. It doesn’t really matter, if your registry is one kilobyte smaller or simply has double its ‘necessary’ size – which in my case would be less than 100 Megabyte.

Do you use your machine for routine work? Is it still much the same it was when you were finished with installing your system and programs? Once in a while you test a program, uninstall it, but not really that often? Well, then probably, there’s not too much going on in your registry. And in that case, why not better leave it alone?

After uninstalling a program, tons of entries are left in the registry. Reg cleaners offer to remove those “orphaned” entries. Alas, after uninstalling quite often more is left behind: the program’s folder and sometime even files. In order to do the job properly, you need a good uninstaller here, not a reg cleaner. If you do not trust or find the program’s own uninstaller use one of ? these programs here.

For years now, registry cleaner are supposed to improve performance, speed, and stability of your system. But where is the hard proof for that? Opinions like “ without a registry cleaner my machine is noticeably slower” don't count. Doesn't your machine also start remarkably more slowly, when you urgently need it? Why are there no objective test results available?

The answer is probably very simple: any test result would very likely show, that “ a cold – untreated – lasts seven days, but when you see a doctor it will be over in just one week!"