Water is essential for human life and makes up over 60% of the human body. It serves many critical functions including transporting nutrients, regulating body temperature, lubricating joints, and removing waste. The average adult needs around 6-8 cups of water per day from foods and beverages to maintain proper hydration, though needs can vary depending on activity level, climate, health factors, and more. Dehydration occurs when the body loses more water than it takes in and can have mild to severe health effects if not addressed.