1) The French Revolution, which began in 1789, marked a major turning point in European history, leading to the overthrow of the monarchy and the rise of republicanism.

2) The concept of 3D printing, also known as additive manufacturing, was first introduced in the 1980s and has since revolutionized prototyping and small-scale production.

3) The Civil Rights Act of 1964 in the United States outlawed discrimination based on race, color, religion, sex, or national origin.

4) The President of the United States serves as the head of state and the head of government, responsible for leading the executive branch and representing the nation domestically and internationally.