Starting from Windows 7, there's a folder %systemroot%\WinSxS which is part of the Windows Side-by-Side system. Incidentally, this folder can become quite large, usually because installing updates or new applications often installs new versions of components in the WinSxS folder while keeping the old versions. There is a way to clean up these old versions by running the command:

dism /online /cleanup-image /spsuperseded

Additionally you can also use the disk cleanup tool to remove old service pack backup files.