What would one use a register cleaner for?

A registry cleaner is a piece of software that allows the user to remove unnecessary entries in the Windows Registry. The Windows Registry is a variety of databases that contain the configuration settings for the Microsoft Windows operating systems. The registry cleaner is particularly useful in removing entries that direct the user to files that are no longer there. According to reviews, a program called "CCleaner" is the best registry cleaner that can be downloaded for free.