The Web has become a ubiquitous tool for distributing knowledge and information and for conducting businesses. To exploit the huge potential of the Web as a global information repository, it is necessary to understand its dynamics. These issues are particularly important for news Web sites as they are expected to provide fresh information on current world events to a potentially large user population. This paper presents an experimental study aimed at characterizing and modeling the evolution of a news Web site. We focused on the MSNBC Web site as it is a good representative of its category in terms of structure, news coverage and popularity. Specifically, we analyzed how often and to what extent the content of this site changed and we identified models describing its dynamics. The study has shown that the rate of page creations and updates was characterized by some well defined patterns that varied as a function of time of day and day of week. On the contrary, the content of individu...