The kidneys are two bean-shaped organs located in the back of the abdomen. They play a critical role in filtering waste and excess water from the blood, forming urine. Each day, the kidneys filter around 120 to 150 quarts of blood to produce approximately 1 to 2 quarts of urine. They also help maintain electrolyte balance, regulate blood pressure, and stimulate red blood cell production. Interestingly, despite their small size, the kidneys receive about 20% of the heart's blood output, underscoring their importance in maintaining the body's internal environment.