20th century — time period between January 1, 1901, and ended on December 31, 2000
The 20th century reshaped human civilization through two world wars, nuclear technology, space exploration, and population growth from 1.6 to 6.2 billion.
Key Facts
- Duration
- 1 January 1901 – 31 December 2000
- Population at start
- ~1.6 billion
- Population at end
- ~6.2 billion
- Position in millennium
- 10th and last century of the 2nd millennium
- Major conflicts
- World War I, World War II, Cold War
- Key scientific shifts
- Theory of relativity, quantum physics, nuclear power
By the Numbers
Cause → Event → Consequence
The 19th century bequeathed a world of industrializing empires, rapid scientific advancement, and rising nationalism. Colonial systems dominated much of the globe, tensions between great powers were mounting, and foundational physics was being reconsidered, setting conditions for dramatic transformation in the century ahead.
The 20th century (1901–2000) encompassed two world wars, the Cold War, decolonization, and sweeping technological change including powered flight, nuclear weapons, digital computing, space exploration, and the Internet. Population nearly quadrupled, democracy spread widely, and women gained suffrage in many nations.
By century's end, a largely globalized world had emerged with near-instant communications, a global economy, and international institutions. Environmental degradation and the ongoing Holocene extinction posed long-term challenges, while medical advances had eradicated or curtailed many infectious diseases and standards of living had broadly risen.