On August 21, the Polish weekly PrzekrÃ³j published an advertisement for Dan-Mark exercise books, bearing the logo of 4fun.tv, a Polish music/interactive   TV station. Part of the advertisement contained a definition of the word "exercise book". The wording looked familiar, and Wikinews consulted Wikipedia,   the collaborative online encyclopedia.  Upon seeing the Wikipedia definition, it appeared that the entry quoted in the promotional material was identical to the initial two paragraphs of the relevant Wikipedia entry.
Wikipedia is an online encyclopedia anyone can edit.