Hemisphere: A mapping division meaning half of the earth (sphere). First, picture cutting the earth in half at the equator (0 degrees latitude). This divides the earth into the Northern Hemisphere (north of the equator) and the Southern Hemisphere (south of the equator). These are labeled in yellow on the illustration.

Next picture cutting the earth in half at the Prime Meridian (0 degrees longitude). This divides the earth into the Western Hemisphere (west of the Prime Meridian) and the Eastern Hemisphere (east of the Prime Meridian). These are labeled in red on the illustration.