A Height Reference System is a standardized method used to measure and define elevations or heights on the Earth's surface. It establishes a baseline, often referred to as a datum, from which all height measurements are derived. This system is crucial for various applications, including mapping, construction, and navigation. Different regions may use different height reference systems, such as the North American Vertical Datum (NAVD) or the European Vertical Reference System (EVRS). These systems help ensure consistency and accuracy in height measurements, allowing for effective communication and data sharing across various fields and industries.