The term "datum" typically refers to a single piece of information, or a specific value that serves as a reference point or starting point for further analysis or measurement. In some contexts, the term may be used in the plural form "data", which refers to multiple pieces of information. In the field of surveying and mapping, a datum is a specific point or set of points on the earth's surface used as a reference for determining the location of other points. This is often referred to as a "geodetic datum". In this context, the datum serves as the starting point for a coordinate system, allowing surveyors and cartographers to accurately map and measure distances and locations on the earth's surface. Overall, the term "datum" can be used in a variety of fields and contexts, but it generally refers to a specific piece of information or a reference point that is used as a starting point for further analysis or measurement.