Nobody wants to talk about poop, but we really should because it can reveal all sorts of things about what's going on inside your body.

According to Dr. David Dragoo, MD, the color and consistency of your stool is one of the most important signs of your underlying health:
Bloody stool is either the sign of hemorrhoids or possibly something more serious like cancer. Bloody stool is a particular one that you want to get checked out if you see that. Of course, on a lighter note, purple/reddish stool might just mean that you've eaten a lot of beets lately! Lastly, green poop is also not a good sign as it may reflect that your GI tract is having issues breaking down your bile and may warrant a trip to the doctor. Be one with your poop and use it to learn about your health and how to improve it!
But don't panic if you suddenly find yourself pooping rainbows, as certain foods can also have an affect on the color of your stool:
Beets or red popsicles can make a red/dark red appearance, and this could obviously be concerning because blood looks similar. Iron supplements can make the stool turn very dark, but tar/black stools could mean a GI bleed as well. If you have biliary system issue your stool may lose that brown/yellow appearance and become "clay" colored.
If there's anything to be learned from all this is that you should not just pay attention to what you eat but what you poop.  If anything seems out of the ordinary or you have been experiencing pain along with your bowel movements, it's best to consult your doctor.