What is Time Zone?
Time zone is each of the 24 time zones into which the Earth is divided, the time it takes for the planet to rotate on its own axis, and which determines the time of a geographical area from the Greenwich meridian, from which hours should be added or subtracted accordingly.
The Greenwich meridian was adopted as a reference for establishing the time zone at the International Meridian Conference held in 1884 in Washington D.C. (United States). It represents the 0° degree of longitude of the Earth, whose imaginary line joins the poles.