Final answer:
Meridians, or lines of longitude, are imaginary lines that encircle the Earth from pole to pole. They are used to measure east-west location, or longitude, and divide the Earth into the Eastern and Western Hemispheres.
Step-by-step explanation:
Meridians, also known as lines of longitude, are imaginary lines that encircle the Earth from pole to pole and intersect the equator at right angles.
The prime meridian, which passes through the Royal Observatory in Greenwich, England, serves as the reference point for measuring longitude. The Earth is divided into the Eastern and Western Hemispheres based on these meridians.