When you poop , the little coloured blob in your toilet bowl is what's left of the food after your body has absorbed all the nutrients it needs from it.
Pooping is vital to your health as it's your body's naturally way of expelling the waste that it doesnt need. How your poop looks and  smells can give clues to what's going on inside your body. Below displays the various type poop there is and what may cause it to have that particular colour other than the norm.
BROWN
You're fine. Poop is naturally brown due to the bile produced in your liver. No Need to see a Doctor.
GREEN
Food may be moving through your large intestine too quickly. Or you could have eaten lots of green leafy veggies or green food colouring.
YELLOW
Greasy foul-smelling yellow poop indicates excess fat, which could be due to a malabsorption disorder like celiac disease.
BLACK
It could mean that you're bleeding internally due to ulcer or cancer. Some vitamins containing iron or bismuth subscalicylate could cause black poop too. Pay attention if its sticky and see a doctor if you are worried.
WHITE
If its not what you're normally seeing it could mean a bile duct obstruction. Some meds could cause this too. See a Doctor.
RED
Blood in your poop could be a symptom of cancer. Always see a doc right away if you find blood in your stool
