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

2) Democracy is a system of government in which power is vested in the people, who exercise it through elected representatives. It allows for political participation, freedom of speech, and protection of individual rights and liberties.

3) The fingerprints of koalas are so similar to humans that they have been mistaken at crime scenes.

4) The phenomenon known as "black holes" occurs when matter is crushed into an infinitely small space, creating a gravitational pull so strong that nothing can escape.