1. World War I (1914-1918) and World War II (1939-1945): These two global conflicts had profound impacts on the world. World War I resulted in the loss of millions of lives and led to the collapse of several empires, including the Austro-Hungarian Empire and the Ottoman Empire. World War II was even more devastating, with an estimated 70-85 million people killed. It also led to significant political and geopolitical shifts, including the rise of the United States and the Soviet Union as global superpowers and the subsequent Cold War.
2. The Russian Revolution of 1917: This revolution led to the overthrow of the Tsarist regime and the establishment of the Soviet Union, the world's first socialist state. The Russian Revolution had far-reaching consequences, both within the Soviet Union and globally. It inspired communist movements worldwide and shaped the course of international politics for decades.
3. Space Exploration and Technological Advancements: The 20th century witnessed remarkable progress in science and technology. Significant milestones included the first powered, controlled flight by the Wright brothers in 1903; the development of computers and the internet; the exploration of space, including the landing humans on the moon in 1969; and the advancement of medical and healthcare technologies, leading to improved life expectancy and quality of life.