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)

Kublai Khan dealt in paper money rather than gold. (TV: Marco Polo)

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) By the 1960s, the UK used pounds, shillings and pennies, (TV: "An Unearthly Child") while most of Europe and the United States used a decimal system. (PROSE: Doctor Who and an Unearthly Child)

The Doctor's money

The Third Doctor carried a bank-note with the image of Queen Elizabeth II. (COMIC: Backtime)

The Seventh Doctor provided money for his companion Ace to purchase food when they visited Shoreditch in November 1963. (TV: Remembrance of the Daleks)

The Ninth Doctor told Rose Tyler that he could not pay for chips as he had no money. Teasingly branding the Doctor a "tightwad", Rose proceeded to pay for their chips. (TV: The End of the World) Later, however, the Doctor proved able to obtain money from a cashpoint aboard Satellite Five in the year 200,000 using his sonic screwdriver. Providing a card of unlimited credit to Adam Mitchell, the Doctor deemed it "pocket money". (TV: The Long Game)

On 24 December 2007, the Tenth Doctor informed Donna Noble that he had no money. He was, however, able to use his sonic screwdriver to produce notes from an ATM. (TV: The Runaway Bride)

Shortly following his regeneration, the Twelfth Doctor, lacking money, gave his watch in exchange for a coat worn by Barney the tramp in Victorian London. Even after returning to the TARDIS, where he changed his clothing, the Doctor informed Clara Oswald that he had no money to buy coffee in 21st century Glasgow. (TV: Deep Breath)

Entering a diner, the Twelfth Doctor told the waitress that he had no money, but he could play the guitar for her, which she accepted. Unbeknownst to him, the waitress was actually Clara, the memory of whom he had lost. (TV: Hell Bent)