I have seen that there are many “titular bishops” and “titular sees” out there. These sees seem to be occupied by members of the Curia or by auxiliary bishops who work nowhere near their see. (Source: catholic-hierarchy.org). Some of these titular sees are in the United States (Alton, Allegheny, Kearny, Walla Walla).
What is the purpose of these titular sees? Does a titular bishop have any rights or duties there? Could these someday be promoted to be a regular diocese?