Collection is to count the number of different books or other literary works. When counting books, a whole secretary makes a volume, including a magazine, newspaper and other publications. Although publications often contain works by different authors, they can only be counted as one volume in one issue.

In addition, when keeping books, especially in libraries, it is often necessary to collect 3-5 books with the same edition and the same period to ensure readers' reading and loss. Individuals who collect books often have no copies because of their limited ability, while electronic platforms only need to make beautiful backups because of the reproducibility of electronic information and the lossless reading.