That is, it deletes all the files that have been copied, all the Registry keys the installer created, and so forth. The uninstaller goes through the log file and undoes all the changes done during installation.
When a user tries to remove a program through the Add/Remove tool, Windows looks for the registered uninstaller inside the registry and executes it.
During installation, all these operations for installing are logged in a special log file (for example, setup.log), and the installation program usually puts that file inside the application's folder along with the uninstaller. After this is done, a key is added to the Windows Registry, where the Windows Add/Remove tool looks for installed programs. For example, if you install Microsoft Word, then you will also be able to open Microsoft Word documents. The installer can make changes inside the Registry if a shared library needs to be registered or if certain types of files need to be associated with the program being installed. This is a database where all the settings and options for the operating system are stored, as well as for any applications or OS components that are programmed to use it. After that, the installer makes some changes inside the Windows Registry. Other files, such as drivers or shared libraries (again), are copied into the WINDOWS\System32 and WINDOWS\System32\drivers folders. Some files, such as shared libraries (.dll files), will be copied into a folder inside Program Files called Common Files. When you download a program, the files are copied to a specified folder, which is usually somewhere inside the Program Files folder. Several things happen during the installation of a program, which can help explain why you are having difficulties uninstalling it: What You Need to Know About Installing and Uninstalling Programs First, however, I will try to explain what happens during installation.