What are Lavan's Terafim and Why did Rachel Steal Them?

There is an interesting side story in the midst of Yaakov's flight from Lavan's household. Rachel steals her father's terafim, and Lavan accuses Yaakov. Yaakov unwittingly curses the thief, and Rachel dies. Why did Rachel steal them? What are the terafim? We look at different places in Tanakh where terafim are mentioned, and consider different opinions regarding their purpose: are terafim used as an idol worship device, or as a divination tool? 

As we trace the terafim and the motivations of those who use them, we notice patterns that crop up. What emerges is a message about deceit: though on some occasions it may  be necessary, deceit has a price - sometimes a steep one.