[p]TrackMania² Stadium is the return of the popular Stadium environment enjoyed by millions of players with TrackMania Nations Forever. Now part of the ManiaPlanet environment, Stadium allows for improved services around the game, better graphics and a powerful track editor.
Most popular community and official game content for the past week.  (?)
What does popular mean?
It means the content you're seeing has been rated up more than it has been rated down for the given time period.