Whenever you install software on your machine it will leave necessary entries on your machine especially in your Registry. Most software comes with an Installer and an Uninstaller, but not all software is uninstalled properly so that it cleans up after itself. It's not necessarily the software's fault as there can be many reasons for the program not being able to clean up after itself. You might have an anti-virus that prevents a complete uninstall or another program that has blocked the uninstall process. There could be specific reasons for leaving traces in the Registry as a service for the user if he plans reinstalling the product and therefore leaves information behind. But there is also sloppy software that just hasn't been written well and leaves Entries behind.
This is where WinMaximizer helps you out by finding unnecessary leftover Entries and erasing them. WinMaximizer will search uninstall registry areas to confirm that a valid file path exists to the files listed. If the uninstall path to the file does not exist, the item's placeholder in the registry will be removed.