What does longitude measure?

Longitude measures the distance in degrees east or west of the prime meridian, which is an imaginary line that runs from the North Pole to the South Pole. This system allows for the identification of specific locations on the Earth's surface in relation to the prime meridian, which is defined as 0 degrees longitude. Each degree of longitude represents a distance that varies with latitude, but understanding longitude is essential for navigation, cartography, and geography as it helps in determining time zones and the positioning of geographical features.

The other options focus on different geographical measurements. One option discusses latitude, which is related to measuring distances north and south from the equator. Another refers to total distance traveled, representing a different aspect of travel than angular measurement. The last choice discusses elevation, which is not related to the concept of longitude at all.