Excretion is the biological process by which waste products, such as metabolic byproducts and excess substances, are eliminated from an organism’s body. It is essential for maintaining internal homeostasis and preventing the accumulation of harmful substances. Excretion helps regulate the composition of bodily fluids, removes nitrogenous waste (e.g., urea in mammals) produced during metabolism, and expels excess ions and toxins. Efficient excretion ensures proper osmoregulation, acid-base balance, and overall metabolic stability. In multicellular organisms, excretory organs, like the kidneys in humans, play a vital role in filtering and eliminating waste, promoting the health and functionality of the organism.