Tableau Server has grown beyond its original scope and now needs to tighten permissions to control access. It is used by multiple external organizations and users. Each publisher will need to consider who can access their workbooks, views, and data sources, as the default "All Users" permission will be banned. Tableau Server permissions are evaluated at the data source, workbook, view, site, and project levels to restrict access. Common user roles include Interactor, Publisher, Editor, and administrative roles.