According to Wikipedia: 

"Bookland" is the informal name for the Unique Country Code (UCC) prefix allocated in the 1980s for European Article Number (EAN) identifiers of published books, regardless of country of origin, so that the EAN namespace can catalogue books by ISBN rather than maintaining a redundant parallel numbering system. In other words, Bookland is a fictitious country that exists solely in EAN for the purposes of non-geographically cataloguing books in the otherwise geographically keyed EAN coding system.  

According to Us: 

Bookland is a country you reach through reading, through talking about books with your friends, and through hanging out in your local bookshop. Though we issue passports for Bookland, the territory it encompasses spans the entire known world, plus quite a few as yet unexplored dimensions, and also exists across the totality of the Temporal Realm. Bookland's National Motto is LIBRI SINE TERMINO, which can translate two ways, either as "Books Without Borders" or "Books Without End". All indie bookshops are unofficial Embassies of Bookland, and any can become an Official Embassy simply by issuing passports which can be supplied by emailing the mysterious Secretary to the Grand High Ambassador of Bookland. Citizens of Bookland don't need documentation to prove their status... but it sure is fun!