First of all, the system will naturally produce various files during operation, so the volume will become larger and cannot be compared with the volume when the system was just installed.

Generally, files generated from Windows directories are basically Microsoft's own things. For example, Windows Update updates the generated files. Located at c: \ windows \ Software Distribution \ Download.

There are also system files backed up by Microsoft system, which are used for recovery when files in directories such as System32 are deleted by mistake. In C:\Windows\winsxs (Note, if you don't know this folder, don't move it casually, or the system will crash. )

There is also the installation package software made by Windows Installer, which will generate software uninstall data in C:\Windows\Installer.

Especially the directory winsxs, this folder takes up a lot of space, so we recommend a software to optimize and streamline this folder. The software name is Dism++ (only systems above Win7 are supported. )

Win 10 upgrade notice can uninstall update patch KB3035583. Win 10 has not been released, so the system has not downloaded Win 10.