1) The assassination of Archduke Franz Ferdinand of Austria in 1914 triggered the start of World War I.

2) The concept of federalism involves the division of powers between a central government and regional or local governments, allowing for shared governance and autonomy for different levels of administration.

3) George Clooney is an American actor, filmmaker, and activist. He gained fame for his role in the television series "ER" and has since starred in successful films such as the "Ocean's" trilogy, "Syriana," and "Up in the Air," winning several awards for his performances.

4) The world's first stock exchange was established in Amsterdam in 1602.