Internal hydration refers to the process by which the body maintains proper fluid balance to ensure optimal functioning of bodily systems. This includes the regulation of water intake, absorption, distribution, and removal within the body. Proper internal hydration is essential for maintaining overall health and well-being, as dehydration can lead to various health issues such as fatigue, decreased cognitive function, and impaired physical performance. Researchers in this area study the mechanisms of internal hydration, factors influencing fluid balance, and methods to optimize hydration status for improved health outcomes.