Many non-Catholics wonder why the Pope and most Catholic clergy wear what resembles to be a yarmulke, the little jewish skullcap. To be accurate the Pope does not wear a yarmulke or kippah, but a zucchetto, a name which comes from the Italian expression little gourd, as for the vegetable zucchini, since the hat resembles a small pumpkin cut in half. However, the official Latin name for the Pope’s cap is pileolus. It is also called Soli Deo, Latin for God alone, to denote that those wearing such hat have consecrated their lives to the Lord.
According to Catholic hierarchy, different color pileolus denote different status within the Catholic clergy, thus the Pope wears a white zuccheto, cardinals wear red ones, bishops wear purple and priests wear black zucchetos. This tradition dates back to the old testament, in which jewish priests were required to cover their heads in the presence of God as a sign of humility.