The Astronomical Unit (AU) is more than just an answer to the question "How far away is the Earth from the Sun" - it also provides a vital tool for surveying the universe, because it offers a fixed unit with which to compare vast distances across space.

What country does au stand for?

Computing. .au, the internet country code for Australia.

What does au stand for in writing?

An alternative universe (also known as AU, alternate universe, alternative timeline, alternate timeline, alternative reality, or alternate reality) is a setting for a work of fan fiction that departs from the canon of the fictional universe that the fan work is based on.