I belive they are the great gatherings of public information and literature that are owned and run by the Government itself.
Websites that catalog and contain vast amounts of data, books, and media which are owned by the Government.
You know how some places like here collect art work, and how places like FIMFiction gather MLP fan fics?
There are online libraries of books and information that are funded and helped by the government,to ensure that things like Dictionaries, thesaurus, Classical, and informational texts are always available for people to use.