The Windows Registry is a massive collection of files that records practically everything that happens on a computer, from a Web site visit to a programme installation. Drivers and other vital programmes, such as DLLs (little helper programmes that commonly function with several applications), are also listed in the registry. This data is saved in the form of "keys" that aid programme execution. It's a big plan for where everything belongs on your computer and how everything works together. Registries are found only on machines running Windows operating systems, and despite reports to the contrary, Windows 7 will include one.

Hundreds of thousands of entries can be found in a registry, and new ones are added all the time. The registry may slow down a computer's speed when it fills up with data. One issue is that, even when a software is uninstalled, Windows usually never removes registry entries since most uninstallers can't efficiently remove their own registry keys. Some registry keys point to programmes or files that no longer exist or are placed elsewhere as files are moved around and programmes are uninstalled.

These inaccuracies, fortunately, do not have to be condoned. It is possible to clear out the register, but not fully. In exchange for your troubles, you might gain improved performance and a shorter boot time. Some happy customers say there's less lag and Windows hanging (when the machine doesn't respond). The actual performance gain depends on the registry's status and the effectiveness of the cleaning tool used. Although most registry entries are fairly short, you can also free up storage space.

Cleaning the registry is not without risks. This is a really sensitive region of your computer, so don't mess with it if you're pleased with how it's working. Attempting to manually alter your registry can result in registry issues that prevent Windows from loading. Important registry keys and DLL files have been reported to be deleted by some registry-cleaning tools. And the performance gains could be minor, given that running the programme and authorising each recommended deletion could take several hours. Furthermore, solid information on how registry cleaners effect performance is nearly impossible to come by. The majority of "performance tests" are actually created by registry-cleaning software developers.

Despite these concerns, cleaning out some of the registry's muck is achievable, and your computer may benefit as a result. On the following page, we'll look at how to approach this difficult task.

It's better to establish a backup copy of the registry and store any vital data to an external hard drive or disc before messing about with it. Some registry cleaners provide a feature that allows you to back up a copy of your system's registry. If not, a quick search on the Internet should yield a free backup tool.

The registry can be edited with a built-in tool in Windows. It's called regedit.exe, and you can get to it by going to the Start menu, selecting Run, and entering in the program's name. Although this programme is simple to find, it is complex to use. The names of registry entries are long and oblique, and they don't tell you much about what they represent. Even experienced computer users may be unaware of what a particular entry refers to. It's better not to use regedit.exe unless you have detailed instructions for how to change or delete a clearly defined item.

There are a plethora of third-party registry-cleaning tools available that take care of a lot of the tedious mechanical work of analysing and deleting registry entries. Check through reviews on sites like ZDNet, CNET, PC World, and PC Magazine to discover a programme that meets your needs. Some of these tools are free, while others only repair a few entries at a time, which can be time-consuming when a registry contains 2,000 faulty entries. Others may cost $20 or more and be included in a system utility package.

Cleaning a registry more than once a month isn't necessary. Additional performance gains may be obtained by using a disc defragmentation tool.

Make sure you close any other open programmes, as well as those running in the system tray next to the clock in the bottom right corner of your screen, before opening the software you've chosen. Pay attention to the following instructions: Most of these cleaner tools are simple to use, checking the registry for mistakes and then providing options for fixing broken entries. However, if you click frantically and try to rush through the process, you may miss an essential step or warning.

Some experts advise against using programmes that erase registry mistakes automatically [source: Bass]. It's preferable to manually authorise deletions. The cleaner will most likely present you with a list of registry entries that you can safely delete because they are no longer needed. It might also offer the opportunity to "fix" a record. Going further and deleting borderline entries could have an impact on a program's capacity to run — for example, deleting a DLL that the cleaner doesn't recognise is shared by multiple programmes — or you could permanently destroy your Windows installation. If in doubt, leave the entry alone.

That's all there is to it. Hopefully, you were able to delete a few hundred entries without causing your computer to crash. If not, you won't be interested in the links on the next page regarding registry cleaners and other relevant issues because you won't be able to read this.