Fluid replacement is the process of replenishing fluids lost from the body due to activities like exercise, illness, or heat exposure. It is essential for maintaining proper hydration, which supports bodily functions such as temperature regulation, nutrient transport, and waste elimination. Common fluids used for replacement include water, sports drinks, and electrolyte solutions. During physical activities, especially in hot conditions, the body loses fluids through sweat. To prevent dehydration, it is important to drink fluids before, during, and after exercise. Monitoring signs of dehydration, such as thirst, dark urine, and fatigue, can help ensure adequate fluid replacement and overall health.