Excretory describes the body systems and organs that remove waste products. Your excretory system includes your kidneys, which filter your blood and make urine, your bladder, which stores that urine until you're ready to use the bathroom, and other organs that help your body get rid of things it doesn't need.

Every living thing creates waste as it goes about its daily activities. When your cells use food for energy, they produce waste products like carbon dioxide and urea. These waste products would become toxic if they built up inside you, so your excretory system constantly works to remove them. Your lungs are part of this system too: they excrete carbon dioxide every time you breathe out.

The word comes from the verb excrete, which means to separate and remove waste from the body. Different animals have different excretory systems. Fish excrete waste through their gills and skin. Insects have special tubes that filter their body fluids. But all these systems do the same essential job: keeping the body clean and healthy by removing what it doesn't need.