The Windows Registry is a database in which Windows and application programs store all manner of configuration settings, startup information, hardware settings, user preferences, file locations, license and registration information, last-viewed file lists, and so on. In addition, the Registry stores the associations between file types and the applications that use them. For example, the Registry holds the information that tells Windows to use Media Player when you click on an MPG movie file. In the early days of DOS and Windows, programs stored this kind of information in a random collection of hundreds of files scattered all over your hard disk. Thankfully, those days are only a dim memory.