An imaginary line that runs through Greenwich, England and divides the world into the eastern and Western Hemisphere

The imaginary line that runs through Greenwich in England and divides the world into the eastern and Western Hemisphere is the prime meridian.

In an International Conference in Washington in 1884 they decided the Observatory of Greenwich would be the initial meridian for longitude.

The Greenwich meridian terminates at the North Pole and South Pole and is the reference for the zero location in longitude.

The prime meridian is also the base for World Time Zone.