A subdirectory is a directory that is located within another directory. A similar term can be used to describe a folder beneath another folder in a GUI (graphical user interface) like Microsoft Windows. Below are some additional examples of subdirectories and subfolders.
In the above MS-DOS prompt subdirectory example, "Windows" is a subdirectory of the "System32" directory.
In the above Linux example, "home," "user," "c," and "computerhope" are all subdirectories of the public_html directory. Any directory below the current directory is considered a subdirectory regardless of how deep it is in the path.
Like a subdirectory, a subfolder is any folder that is a parent of another folder. In the example below, the Windows folder is a subfolder of the Fonts and System32 folders.