The most cutting-edge information systems support selective information dissemination, filtering, hypertext, distributed database administration, digital document preservation, and distributed database administration. Websites devoted to the construction and upkeep of electronic book collections and other types of content are known as "digital libraries," and they do so without asking that users pay for the books and other content they wish to access and read. Part of what makes digital libraries so exciting is the involvement of a sizable number of intermediate institutions in the creation and preservation of these collections.