Human kidneys are bean-shaped organs located on either side of the spine, just below the rib cage. They filter blood to produce urine, remove waste, and balance electrolytes. Each kidney contains around one million nephrons, the functional filtration units. The kidneys regulate blood pressure, maintain homeostasis, and produce hormones like erythropoietin and renin. They filter about 180 liters of blood daily, producing 1-2 liters of urine. Proper kidney function is essential for overall health and metabolic balance.