Hectare (ha)
The hectare, or ha, is a metric area unit equal to 10,000 square meters (a square with 100-meter sides). First used in France in 1795, it is now widely used worldwide, particularly in farming, forestry, and land planning. Although it is not an official SI unit, it is permitted because it is practical for measuring fields and properties. Its simple size makes it better than the square kilometer for medium areas.
Square Kilometer (km²)
The square kilometer, or km², is equal to one million square meters. It was designed for measuring large areas when the metric system was introduced. Square kilometers are often used in geography, maps, and environmental studies to represent the size of places such as cities, forests, and countries. For example, a country’s size is typically measured in square kilometers (km²). Its ease of use and simple conversions make it important for sharing global information.