Hyperinflation
Regular inflation means prices rise gradually over time. Hyperinflation means they rise so fast that money loses meaningful purchasing power within days or even hours. The 50% monthly threshold — meaning prices more than double every few months — comes from economist Phillip Cagan's landmark study of historical episodes. Weimar Germany in 1923 and Zimbabwe in the late 2000s are among the most cited examples.
Hyperinflation almost always stems from a government printing large quantities of money to cover debts or deficits, collapsing the public's trust in the currency. Once people expect prices to keep rising, they spend money immediately rather than save it — which itself accelerates the price spiral. The currency's exchange rate typically collapses against foreign currencies at the same time.
In market data, hyperinflationary environments are visible in astronomical year-over-year CPI readings and in emerging market currency charts that show near-vertical declines. Historically, hard assets like gold and foreign currency holdings have been where populations sought refuge, though past behavior in specific crises doesn't predict future outcomes elsewhere. Economists read hyperinflation as a failure of monetary credibility, not merely an extreme version of ordinary price pressure.