I edit here since the end of December 2006 (then only as an anonymous "IP-Wikipedian"); from June 2007 I have been duly subscribed. I mainly focus on the areas where I have been educated (either at university or as a self-taught-enthusiast) and for which, guess, I have an understanding of:
Sometimes I dip into geography, general culture and rarely also into technical and natural scientist spheres.
Furthermore, I struggle for improvement of language and stylistic qualities of the English Wiki. (Although I am not native speaker.) Many articles here are poorly written both grammatically and stylistically, one sometimes has the feeling that he read essays of primary school pupils... Such phenomenons reduce the informational value of Wiki.
