The kidneys are vital organs that filter waste and excess substances from the blood. They help maintain the body's balance of fluids, electrolytes, and acids. Each kidney contains about a million tiny filtering units called nephrons, which remove toxins and produce urine for excretion. In addition to waste removal, the kidneys play a role in regulating blood pressure and producing hormones like erythropoietin, which stimulates red blood cell production. Proper kidney function is essential for overall health, as it helps prevent the buildup of harmful substances in the body and supports various bodily processes.