Registry First Aid is a Windows Registry backup and maintenance tool. The application's main objective is to detect errors in the registry and fix them by eliminating duplicate entries or entries that lead to nowhere (in lay terms). For doing that, Registry First Aid uses an internal scanning engine to determine which registry entries are wrong. It can detect invalid paths, invalid file associations, invalid fonts, invalid application paths, among other invalid entries. It then evaluates how safe it is to delete these entries and gives you that information. The application gives you a list of entries with a green icon next to them; those are the safest to delete, followed by yellow. Obviously, the red ones are not to be deleted if you don't know what you are doing.
Other than the usual registry maintenance, Registry First Aid also allows you to defragment the registry and to manage it in a variety of ways. You can use it to search the registry for keyboards and you can create backups of the whole registry that you can later restore. There is also an option to manage the registry, although it is not available in the trial version. There are some limitations for the trial. You can't clean more than 20 entries per session and, as I have mentioned, some features are not available.
