c:\\$extend, what is this folder?

Sometimes when you scan the hard disk with some tools, the $extend folder will be found in the NTFS partition root directory (of course, if your hard disk partition format is FAT32, I will see it.) Some tools may report that the $extend folder is very large, but don't just clean it up (you can't see it directly, unless you use PowerTool, XueTr, etc. Or you can see it and operate on the PE system. If you delete the file or folder in the file, you may not be able to enter the system, or even reinstall Windows, because the $extend is saved. The important files of NTFS are so simple to say, it is important.

If the problem is minor, may be checked by ScanDisk program chkdsk to repair, such as windows 7 will prompt.