The 404 Book focuses on the concept error. Its objective is to enlighten the reader into my perception of errors in general. The number 404 (derived from the famous “Error 404 – Page Not Found”) was chosen as a comprehensive tool for all the different errors. For example: the book exactly comprises 404 pages, and the sum of the width (in millimeters) with the height equals 404mm, but still retaining the DIN A-proportions. The book is divided in 3 major parts. The first part, called PRE 404, shows different kinds of errors that were gathered between October 2011 and April 2012, and depending on the specific subject a little project would come about (e.g. a pantgraph was built, a found image was painted, illustrations were made, posters were designed, etc.). The results of these little projects are shown in the book, as well as some research that was done on the different kinds of errors. Every error is introduced by a short text. This chapter intends to establish relationships between the different kinds of errors. The second part, simply called 404, explains the origins of the number itself, as well as some false myths that exist around the mythical number 404. After the disquisition of its origins, the 404 chapter also shows how the number is used for other purposes (e.g. a Bollywood movie, a NYC restaurant, etc.). The final part, called ARTISTS APPENDIX, is, quite obvious, an appendix, where in true catalogue-style all the different artists are shown, that had any kind of influence on the previous chapters. A Reference List rounds up this chapter, by briefly explaining which specific part of the book it influenced, and how.