/ Stands for the root directory, the root directory: the root directory refers to the uppermost directory of the logical drive, which is relative to the subdirectories. Open "My Computer", double-click the C drive to enter the root directory of the C drive, and double-click the D drive to enter the root directory of the D drive.
The reason why it is best not to use is because the path is easy to expose; the relative path of the root directory: refers to the path from the site folder to the linked document. All public files on the site are stored in the root directory of the site.
…/ represents the upper level directory
…/…/ represents the upper two-level directory
/... represents the subordinate directory
/.../... represents the next two levels of directories