The 30th Anniversary Conference on Current Trends in Theory and Practice of Computer Science, SOFSEM 2004, took place during January 24-30, 2004, ´ in the Hotel VZ M? e? rin, located about 60 km south of Prague on the right shore of Slapsk´ap? rehrada ("Slapy Dam") in the Czech Republic. Having transformed itself over the years from a local event to a fully internat- nal conference, the contemporary SOFSEM tries to keep the best of its winter school aspects (the high number of invited talks) together with multidiscip- narity trends in computer science - this year illustrated by the selection of the following 4 tracks: - Computer Science Theory (Track Chair: Peter Van Emde Boas) - Database Technologies (Track Chair: Jaroslav Pokorny) ´ - Cognitive Technologies (Track Chair: Peter Sin? c´ ak) ? - Web Technologies (Track Chair: Julius ´ Stuller) Its aim was, as always, to promote cooperation among professionals from a- demia and industry working in various areas of computer science.