There are three classes of cardinals. Cardinal bishops are the bishops of seven sees around Rome (Ostia, Velletri, Porto and Santa Rufina, Albano, Frascati, Palestrina, and Sabina and Poggio Mirteto) and Eastern-rite patriarchs; the first of these in order of creation is dean of the college and ex officio bishop of Ostia in addition to his other see. Cardinal priests are mostly archbishops outside the Roman province; the title "cardinal archbishop"—often applied to these men—simply represents the union of the two dignities in one man. Cardinal deacons are priests with functions in the papal government. Cardinal priests and cardinal deacons have titles corresponding to churches of the Roman diocese.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.