1) The process of nuclear fusion powers the sun and other stars, fusing hydrogen atoms together to form helium and releasing vast amounts of energy in the process.

2) The European Union (EU) is a supranational organization comprising 27 member states that cooperate on various issues, including trade, economic integration, and common policies, while preserving individual national sovereignty.

3) The invention of the printing press by Johannes Gutenberg in the 15th century revolutionized the spread of knowledge and played a key role in the Renaissance.

4) A group of flamingos is called a "flamboyance."