A vertical datum is a reference point or surface used to measure elevation or depth. It serves as a baseline for determining the height of land features, buildings, and other structures. Common examples of vertical datums include the North American Vertical Datum of 1988 (NAVD 88) and the Mean Sea Level (MSL). Vertical datums are essential in fields like geodesy, engineering, and cartography. They help ensure consistency in measurements across different locations and projects. By providing a standard reference, vertical datums facilitate accurate mapping, construction, and land surveying activities.