This piece of the pope’s clothing is a small, round skullcap. Amongst the clergy, the color of the zucchetto denotes the wearer’s rank, and lower ranking members must always remove their zucchetto in the presence of a higher ranking member of the clergy. It is usually made from silk, and features eight triangular panels joined to form a circle.
The highest color, white, is worn by the pope. Next is scarlet, worn by cardinals, and then bishops, who wear amaranth. Meanwhile, priests and deacons wear black.
One interesting note about the zucchetto is that, if a visitor offers the pope his or her own zucchetto, the pontiff will often remove his and replace it with the gift, giving his old one to the visitor. Pope Benedict XVI and, more recently, Pope Francis, have done this often. So if you want a papal keepsake, bring a zucchetto with you the next time the pope is speaking!
Like the cassock, the zucchetto is a marker of the clergy, helping the church leadership to stand out and take on a uniform and organized appearance.