Urine is the liquid waste that your body produces to get rid of extra water and chemicals it doesn't need. Your kidneys act like filters, cleaning your blood all day long and collecting the waste in a yellowish liquid that you release when you use the bathroom.

Your body is constantly working to keep the right balance of water and minerals. When you drink a lot of water, your urine becomes lighter in color because your body is flushing out the excess. When you haven't had much to drink, your urine gets darker and more concentrated. That's why doctors often tell you to drink more water if your urine is very dark yellow.

Urine is the medical term for what people also call pee. Doctors can learn a lot about someone's health by testing their urine, checking for signs of dehydration, diabetes, or infection. Animals produce urine too, and some animals even use it to mark their territory or communicate with each other.