Catalogue: refers to a tool that records a number of related documents and arranges them in a certain order to reveal and report them. It is a bridge and link between literature and users. It is the epitome of books and articles.

"Directory" is a general term for contents and records. "Mu" refers to the title of an article or a book, and "Lu" is the explanation and arrangement of "Mu". The predecessors distinguished "Mu" and "Lu". Together, it is called a "directory".

Now, the word "directory" has been used as a noun. In modern Chinese, the meaning of the word "catalogue" is: first, it is the abbreviation of "book catalogue". This catalogue records the titles, authors, publications and collections of books in a certain order, and is a tool to reflect the library model, guide reading and retrieve books. The second refers to what I wrote before the text of the book. In addition, according to a certain subject, a bibliography compiled for special research or a recommended bibliography introducing excellent reading materials to the masses is generally called a bibliography, and sometimes it is also called a catalogue.