Our Sedra details the clothes worn by the Kohanim; one of them is the "mitznefet," assumed to be a turban made of fabric wound around & around, but which Rashi calls a "kipa" or tall hat. The tradition to wear a kipa is not derived from any biblical verse. Rather, it is a custom which evolved as a sign of our recognition that there is someone above us who watches our every act. This is the meaning of "yarmulka" – literally, "Yare Malka," or "fear of the King." The Gemara in Shabbat tells of a woman who was told by astrologers that her son would be a thief; she made sure that his head was always covered so he would overcome his urge to steal. In Talmudic times, wearing a head covering was reserved for men of great stature. In later generations, though, it became the accepted custom for all Jewish men to wear a kipa at all times, especially during prayer. As with all Jewish customs, once they become universally accepted practice, they take on a more obligatory status.