Thirst is the body's signal that it needs water or fluids. It occurs when the body loses more water than it takes in, leading to dehydration. This can happen due to various reasons, such as physical activity, hot weather, or illness. The sensation of thirst is controlled by the brain, which detects changes in the body's hydration levels. When a person feels thirsty, it is important to drink fluids to restore balance. Water is the best choice, but other beverages and foods with high water content can also help. Staying hydrated is essential for overall health, as it supports bodily functions like digestion and temperature regulation.