To excrete means to get rid of waste materials from your body. When you use the bathroom, you're excreting waste that your body doesn't need anymore. Animals excrete too: birds excrete droppings, and even plants excrete waste through their leaves.

Your body is like a factory that constantly processes food and water. It takes what it needs (nutrients, energy, water) and has to dispose of what's left over. Excretion is the process that makes this happen. Your kidneys filter waste from your blood and turn it into urine. Your intestines package up solid waste. Your skin excretes some waste through sweat.

Different organisms excrete in different ways. Fish excrete waste directly into the water around them. Insects excrete through tiny tubes in their bodies. Even microscopic bacteria excrete waste products into their environment.