1) J.K. Rowling's "Harry Potter" series of books has sold over 500 million copies worldwide and has been translated into 80 languages.

2) The Sahara Desert, located in North Africa, is the largest hot desert in the world, covering an area of about 9.2 million square kilometers (3.6 million square miles). It is characterized by vast stretches of sand dunes, rocky plateaus, and extreme temperatures.

3) The Russian Revolution in 1917 resulted in the overthrow of the monarchy and the establishment of a communist government under Vladimir Lenin.

4) The Cuban Missile Crisis in 1962 brought the United States and the Soviet Union to the brink of nuclear war during the Cold War.