I'm reading Operating System Concepts by Avi Silberschatz(9thE), in chapter 11 File-System Interface, when the author explains the concepts of file, he states that
The information about all files is kept in the directory structure, which also resides on secondary storage. Typically, a directory entry consists of the file’s name and its unique identifier.
I think the directory structure that holds the information of all files is of critical importance， which the author does not extend in depth though. I don't even know the terminology for this concept of directory structure. It should be somewhere on the disk and well maintained. Could anyone clarify it for me? Any literature and links will be appreciated.
Thanks in advance!