Urim and Tumim- What is their Significance?

In this shiur, we take a closer look at the mysterious Urim ve-Tumim. What are they? Why do they have a double name? What is their purpose? Strangely, it appears that there is no explicit command to make them, yet their presence is assumed by the Torah, and they seem to play a significant role when leaders call for the kohanim to advise them about decisions to make.