The book cell or public bookcase is a format that is used to offer books free of charge, anonymously and in an uncomplicated way. Since the 1990s, such places have been created in urban areas in the form of book boxes, shelves, converted telephone boxes or garden sheds. They are located in urban or rural contexts. They are always public and freely accessible to all. There are no formalities involved in borrowing them. The weatherproof bookcases, which are either specially built or freely adapted, are financed and supported by various sponsors. All citizens can borrow books and/or provide new books. Whether a book is returned, kept or exchanged is up to everyone. Sponsors include private individuals, foundations, Lions clubs, civic associations and similar organisations. The beginnings of the format lie in artistic installations: Since 1991 by the action artist duo Clegg & Guttmann. At the end of the 1990s, there were the first bookcases for use as a free, open-access library in urban areas in Darmstadt and Hanover.

Promotion of public, free »libraries« / access to books

Since the designer and stage designer Trixy Royeck's design was awarded a prize in a competition organised by the Bonn Civic Foundation in 2002, the concept has found numerous imitators. Based on Trixy Royeck's bookcase, the Cologne architect Hans-Jürgen Greve designed his own model (BOKX) made of steel and acrylic glass, which was optimised for outdoor use.

Duo Clegg + Guttmann, installations as an artistic act; Bookcrossing