the.com/root directory

means The top-level folder in a file system from which every other folder and file descends.

from From the computing sense of 'directory' as a listing of files, established by the 1960s-70s with hierarchical file systems, paired with 'root' — the natural metaphor of a tree growing downward from a single base. Unix and its descendants made the image literal, writing the root directory as a plain slash ('/'), the one address that doesn't point anywhere but itself.