The process by which living organisms maintain a stable internal environment is called homeostasis. Homeostasis refers to the mechanisms that organisms use to regulate and balance their internal conditions, such as temperature, pH, hydration, and nutrient levels, despite changes in their external environment. This is crucial for the proper functioning of cells and overall health. For example, humans maintain body temperature through sweating or shivering, while plants regulate water levels through transpiration. Homeostasis ensures the survival of organisms by enabling them to adapt to varying environmental conditions.