The Windows registry is a very useful thing in your computer.  It stores all the preferences and settings for the software and hardware that’s loaded on your computer.  It also stores individual preferences and settings.  The registry is what makes managing different users on a single machine very easy.  It’s kind of like the central nervous system of your computer.  The best registry cleaner software will help you maintain the registry in good working order.  The Windows registry is notorious for getting cluttered with excess entries that are the result of files getting left behind after the incomplete uninstallation of software and hardware.