A Foswiki site is divided into "Webs", or groups or topics - each one represents one subject, one area of collaboration. Administrators can add, rename or delete webs.
At file level, a Web is a directory located inside the data directory, with text files as topics.
A number of Webs are fixed: System for documentation, Main to store user pages and site-wide preferences, Trash for the topic recycle bin.
Other webs can be created as needed.