The registry is where Windows keeps information about everything it knows about. You can think of the registry as a main information area fro windows or the brain of Windows.
Without the registry Windows will not run. Computer programs that run in Windows are comprised of many parts. Windows keeps up with what all these parts are in the registry and also where they are stored. Another item in the registry is all the different file types (or extensions) on your computer and what program will open them like Adobe Reade is used to open .pdf files. Security information is also kept in the registry on who is allowed to access which programs and how. Programs that automatically run are run by Windows based on information in the registry. Some programs always run when you start Windows and they have stored this information in the registry and Windows looks there to know what to run. Other programs (for instance virus scans) run at a certain time every day or on certain days. Again this information is kept in the registry.
The registry works similar to where you keep lots if information of directions to information. It grows over time and sometimes we quit using something or remove a program and some little pieces get missed. It is useful to clean the registry occasionally (I would suggest every 6 months or so for most people) to get this junk out and often it will speed up your computer. Unless you really know what you are doing or following very specific instructions specifically (that was intentional the double specific) donít go in editing the registry. The slightest wrong change to the registry can crash your computer with the only solution being to reinstall Windows.
There are programs you can buy that will clean the registry ( one of the utilities in Norton Utilities does a good job). There are also free registry cleaning programs. The one I like best is ccleaner (that is a double c) and it is at ccleaner.com. The registry cleaner is the second button on the main page of the program. Another free one I like is Wise Registry Cleaner but it is not as friendly. You will see lots of ads for free registry scanners but what they donít tell you upfront is you have to buy to do the registry cleaning. Also watch out on many of these that pop up on you and say you have registry errors that need fixing as often they are spyware or other malware and then you will need to clean them off. Ccleaner has been around many years and is a good program.
The registry is a major part of Windows that makes Windows easy to use.