The National Library of China (NLC) serves as the repository of the nation's publications, a national bibliographic center, a national center for preservation and conservation of ancient books, as well as the national museum of ancient books. It is formerly known as the Metropolitan Library established in 1909. The NLC houses vast collections covering a complete range of categories. As of the end of 2021, its collection has totaled more than 42.3 million volumes (pieces) with the total capacity of digital resources exceeding 2,497 TB.