1) The Amazon rainforest produces more than 20% of the world's oxygen.

2) The Machu Picchu archaeological site, located in Peru, is an ancient Incan citadel situated high in the Andes Mountains. It is recognized as a UNESCO World Heritage site and attracts visitors from around the world who come to marvel at its remarkable architecture and scenic surroundings.

3) The United Nations (UN) is an international organization founded in 1945 with the goal of promoting peace, security, and cooperation among nations through diplomatic and political means.

4) The concept of civil rights pertains to the rights and freedoms that individuals possess as members of a society, including equality before the law, freedom of expression, and protection against discrimination.