The research material pertains to rural and urban subdialects and dialects of nearly all the Slavic languages spoken in Belarus, Bulgaria, the Czech Republic, Macedonia, Poland, Serbia, Slovakia, Ukraine. The article consists of a theoretical part (dedicated to linguistic research into the Internet, computer-mediated communication) and of two analytical parts. The first of them, more general, is aimed at defining the codes used on the surveyed fan pages and the reasons for creating thereof. The goal of the other analytical part, which consists of detailed considerations, is to present the structure of dictionary posts by using Dawniej tutej – gwara wielkopolska, one of the oldest Polish fan pages dedicated to subdialects.