Why is Australia sometimes called down under?

The term "Down Under" is used to refer to Australia and New Zealand because they are located in the Southern Hemisphere, which is considered to be "down" relative to the Northern Hemisphere, where most of the world's population lives.

Additionally, Australia is often referred to as "the Land Down Under," which is a phrase that originated in the 19th century when British settlers in Australia used it to describe their new home. The phrase has since become a common way to refer to Australia, both locally and internationally.