The 180th meridian, also known as the anti-meridian lies 180° east or west of the prime meridian, These two great meridians form an imaginary circle around the globe. This great longitudinal circle forms the international dateline. Apparently it was chosen because it crosses mainly ocean. But the history of it suggests the French and British competed on whether it should go through Greenwich or Paris, so that's up for debate?
It is a method for co-ordinating the world’s time. New Zealand lies just a few degrees west of this dateline [approximately east 180°] and therefore we're right on the edge of tomorrow, at the beginning of each new day.
If you go east of New Zealand you fly into yesterday, while if you fly towards New Zealand you travel forward in time. New Zealanders live in a world where events occur yesterday. We're always in the future, an interesting place to be.