The 180 degrees longitude line is known as the International Date Line. It is also called the anti-meridian and the 180th meridian. It is both 180 degrees east and 180 degrees west of the Prime Meridian.
According World Atlas, the International Date Line separates two consecutive calendar days. Although the International Date Line runs primarily on the 180 degrees longitude line, it veers away from the exact longitude line in parts of the Pacific Ocean. Changes to the official line are due to requests of countries or islands that are located in the Pacific Ocean and are close to the line.