1) The name "Bluetooth" comes from the 10th-century Danish king, Harald Bluetooth, who united Denmark and Norway.

2) The Taj Mahal, located in Agra, India, is an iconic mausoleum recognized as a UNESCO World Heritage site. It was built in the 17th century by Emperor Shah Jahan as a testament to his love for his wife and stands as a masterpiece of Mughal architecture and a symbol of India's cultural heritage.

3) 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.

4) The Triple Double in basketball refers to a player achieving double-digit totals in three of the following statistical categories: points, rebounds, assists, steals, or blocks.