Short answers, pulled from the story.
Hyperinflation is a very high and typically accelerating inflation that rapidly erodes the real value of a currency. Economist Phillip Cagan defined it in 1956 as a period when the monthly inflation rate exceeds 50 percent, which compounds to an annual increase of 12,874.63 percent. The episode ends only when the monthly rate drops back below 50 percent and remains there for at least a year.
Peter Bernholz analyzed 29 hyperinflationary episodes and found that at least 25 were caused by government budget deficits financed by creating new currency. A necessary precondition is the use of paper money rather than gold or silver coins. War is the most common trigger, because governments cannot cut military spending, tax collection collapses, and borrowing becomes unavailable.
Hungary holds the record for the most extreme monthly inflation rate ever documented, at 41.9 quadrillion percent in July 1946. At that rate, prices doubled every 15.3 hours. When the pengő was replaced by the forint in August 1946, 400 octillion pengős exchanged for one new forint, and the total value of all Hungarian banknotes in circulation amounted to less than one US cent.
Germany's worst inflation hit in 1923 during the Weimar Republic. By late 1923, the Reichsbank was issuing two-trillion-mark banknotes and postage stamps with a face value of fifty billion marks. The highest denomination reached 100 trillion marks, and at the peak one US dollar was worth 4 trillion German marks. On the 20th of November 1923, one trillion old marks were exchanged for one new Rentenmark.
Zimbabwe formally abandoned its local currency on the 12th of April 2009, switching entirely to foreign currencies. At the November 2008 peak, Prof. Steve H. Hanke estimated annual inflation at 89.7 sextillion percent, with prices doubling every 24.7 hours. The Z$100 trillion banknote was issued on the 16th of January 2009, just weeks before the currency was abandoned.
Hyperinflation is almost always ended through drastic intervention: dollarization (formally adopting a stable foreign currency), currency reform introducing a new monetary unit, or shock therapy cutting government expenditures sharply. Ecuador dollarized in September 2000 after its sucre lost 75 percent of its value. The political aftermath typically produces institutional changes such as independent central banks focused on price stability, modeled on outcomes like the German Bundesbank after the Weimar crisis.