The Windows registry is a database that lists all of the configuration settings that determine how Windows looks and behaves. Sometimes, settings that are no longer needed will remain in the registry in case they are ever needed again. There's nothing unusual about this, and this data, while unused, is small in size.
Some products available for free on the Internet suggest the registry needs regular maintenance or cleaning. Occasionally, a registry setting can become corrupt but, in general, the registry is self-sufficient. If you do decide to install a registry cleaner, be sure to research the product and only download and install programs from software publishers that you trust.
Some programs available for free on the Internet might contain spyware, adware, or viruses. Only download and install programs from software publishers that you trust. Even if you trust the website you download the program from, you need to also trust the publisher of the program. For more information, see When to trust a software publisher.
We strongly recommend that you only change values in the registry that you understand or have been instructed to change by a source you trust, and that you back up the registry before making any changes.