* Elevation refers to the vertical distance of a point on the Earth's surface above or below mean sea level.
* Above sea level is positive elevation, often measured in meters (m) or feet (ft).
* Below sea level is negative elevation.
For example:
* The peak of Mount Everest has an elevation of 8,848.86 m (29,031.7 ft) above sea level.
* The Dead Sea has an elevation of about -430.5 m (-1,412 ft) below sea level.
