The process by which plants lose water vapor is called transpiration. It involves the evaporation of water from plant surfaces, mainly through small openings called stomata, which are primarily located on the undersides of leaves. Transpiration plays a crucial role in regulating plant temperature and facilitating nutrient uptake by creating a vacuum that pulls water and minerals from the roots through the plant's vascular system. This process is vital for maintaining plant health and contributes to the water cycle, influencing local moisture levels and climate patterns.