The kidney is a vital organ in the human body, primarily responsible for filtering waste products from the blood and producing urine. Each person typically has two kidneys, located on either side of the spine, just below the rib cage. They play a crucial role in maintaining the body's fluid balance, regulating electrolytes, and controlling blood pressure. In addition to waste filtration, the kidneys also produce hormones that help regulate various bodily functions. For example, they produce erythropoietin, which stimulates the production of red blood cells in the bone marrow. Overall, the kidneys are essential for overall health and homeostasis.