These two factions came to be called Guelphs and Ghibellines respectively. The Guelphs were the supporters of the Popes, the Ghibellines of the Emperors. The Guelphs upheld the temporal supremacy of the Pope: the Ghibellines would separate temporal from spiritual authority. The Guelphs resisted the establishment of complete imperial government in the cities of northern Italy: the Ghibellines, with the glories of the old Roman Empire before their eyes, longed to see Italy welded together into a single nation, and governed and controlled by the strong hands of the emperor.
Source: wiktionary