1) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

2) Kimchi is a traditional Korean side dish made of fermented vegetables, primarily cabbage and radishes, seasoned with chili pepper, garlic, ginger, and other spices. It is a staple in Korean cuisine and is known for its tangy and spicy flavors. Kimchi is rich in vitamins, minerals, and probiotics, making it not only a delicious accompaniment but also a healthy addition to meals.

3) The Age of Exploration, during the 15th and 16th centuries, saw European explorers such as Christopher Columbus and Vasco da Gama reach new lands and establish trade routes.

4) The world's first paper money was created in China over 1,000 years ago.