Money

Money, or cash, (TV: The Categories of Life) was a medium of exchange used to facilitate transactions of goods or services. (TV: The Man Who Never Was)

According to the Twelfth Doctor, "Nothing is protected like money," because it was protected by the best firewalls in the universe. (TV: The Husbands of River Song)

The Sevateem had no concept of money. (AUDIO: Death-Dealer)

In Great Britain, the earliest printed money came about in the 18th century. Before then, wealth was generally stored as gold, gems, or various other high-price commodities. (AUDIO: Death on the Mile)