What does "WO" in front of patent WO 05/006842 mean? Where can I find this patent? In what database do I search for it?
The "WO" prefix indicates it is an international patent application, also called a PCT application, filed with the world intellectual property organization under the patent cooperation treaty.
WO is in fact the code for WIPO (i.e. it doesn't just mean "World"), which you can see here: http://www.wipo.int/pct/guide/en/gdvol1/annexes/annexk/ax_k.pdf
You can see the patent application here: https://patents.google.com/patent/WO2005006842A3/en
See more details, from the official WIPO records, here: https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2005006842