What is poop made of?

About 3/4 of your average turd is made of water. Of course, this value is highly variable - the water content of diarrhea is much higher, and the amount of water in poop that has been retained (voluntarily or otherwise) is lower. Water is absorbed out of fecal material as it passes through the intestine, so the longer a turd resides inside before emerging, the drier it will be.
Of the remaining portion of the turd, about 1/3 is composed of dead bacteria. These microcorpses come from the intestinal garden of microorganisms that assist us in the digestion of our food. Another 1/3 of the turd mass is made of stuff that we find indigestible, like cellulose, for instance. This indigestible material is called "fiber," and is useful in getting the turd to move along through the intestine, perhaps because it provides traction. The remaining portion of the turd is a mixture of fats such as cholesterol, inorganic salts like phosphates, live bacteria, dead cells and mucus from the lining of the intestine, and protein.

Why does poop stink?

Poop stinks as a result of the products of bacterial action. Bacteria produce smelly, sulfur- or nitrogen-rich organic compounds such as indole, skatole, and mercaptans, and the inorganic gas hydrogen sulfide. These are the same compounds that give farts their odor.

Types of Poops

GHOST Poop: The kind where you feel the Poop come out, but there is no Poop in the toilet.

CLEAN Poop: The kind where you Poop it out, see it in the toilet, but there is nothing on the paper.

WET Poop: The kind where you wipe your butt 50 times and it still feels un-wiped, so you have to put some toilet paper between your butt and your underwear so you don't ruin them with a stain.

SECOND WAVE Poop: This happens when you're done Pooping and you've pulled your pants up to your knees, and you realize that you have to Poop some more.

POP-A-VEIN-IN-YOUR-FOREHEAD-Poop: The kind where you strain so much to get it out, you practically have a stroke.

LINCOLN LOG Poop: The kind of Poop that is so huge you're afraid to flush without first breaking it into little pieces with the toilet brush.

GASSEY Poop: It's so noisy, everyone within earshot giggles.

DRINKER Poop: The kind of Poop you have the morning after a night of drinking. Its most noticeable trait is the skid marks on the bottom of the toilet.

CORN Poop: (Self-explanatory)

GEE-I-WISH-I-COULD-Poop-Poop: The kind where you want to Poop, but all you do is sit on the toilet and fart a few times.

SPINAL TAP Poop: This is when it hurts so badly coming out you'd swear it was leaving you sideways.

WET CHEEKS Poop: (The Power Dump). The kind that comes out of your butt so fast, your butt cheeks get splashed with water.

LIQUID Poop: The kind where yellowish-brown liquid shoots out of your butt and splashes all over the toilet bowl.

MEXICAN Poop:It smells so badly that your nose burns.

UPPER CLASS Poop: The kind of Poop that has no odor.

THE SURPRISE Poop: You are not at the toilet because you think you are about to fart but...oops...a Poop!!!

THE DANGLING Poop: This Poop refuses to drop into the toilet even though you know you are done Pooping it. You just pray that a shake or two will cut it loose.

Teflon Coated Poop: Comes out so slick, clean and easy that you don't feel it. No traces of poop on the toilet paper. You have to look in the toilet bowl to be sure you did it!

Gooey Poop: This has the consistency of hot tar. You wipe your butt 12 times and it still doesn't come clean. You end up putting toilet paper in your underwear so you don't stain it. This poop leaves permanent skid marks in the toilet.

Bali Belly Poop: You poop so much you lose 5 kilos.

Floater Poop: Even after the third flush, it's still floating in there. My god! How do I get rid of it? This poop usually happens at someone else's house.

After examining this area and the many different processes you can go through, we will examine the actual colors and why they are as such.

Why is poop brown?

The color comes mainly from bilirubin, a pigment that arises from the breakdown of red blood cells in the liver and bone marrow. The actual metabolic pathway of bilirubin and its byproducts in the body is very complicated, so we will simply say that a lot of it ends up in the intestine, where it is further modified by bacterial action. But the color itself comes from iron. Iron in hemoglobin in red blood cells gives blood its red color, and iron in the waste product bilirubin gives rise to its brown color.

What is the cause of yellow poop?

According to Michael F., one cause of this is Gilbert's Syndrome. "I have a benign condition known as Gilbert's Syndrome. It affects quite a few people, males mostly, in their teens+. It is a deficiency in the liver where red blood cells are broken down. I was informed when this was diagnosed that the broken down blood cells is what gives poop a lot of its color. People with Gilbert's Syndrome don't process as many blood cells - or not as fast - and their poop tends to be pale brown or yellow from the lower quantity of discarded red blood cell matter. This is especially true if there is less matter in your intestines (i.e., on a diet - as I have noticed) to remove the excess blood cells. Very frightening until you determine what is causing it. Gilbert's is a totally benign thing that doesn't harm anyone, although when a person is sick they can turn yellowish as if jaundiced, but it is not jaundice."
Another cause of yellow poop is a giardia infection. Giardia are tiny Protozoan parasites that can invade the intestines and result in severe yellow diarrhea. It is a dangerous and contagious affliction that doctors are obligated to report to the Center for Disease Control.

What is the cause of green poop?

Healthy people can have green poop if they eat a diet rich in leafy green vegetables, or if they consume large quantities of food coloring (in ice cream, cake frosting etc.).
Green poop can also be caused by excess iron in the diet, from dietary supplements, for example. If the body does not absorb all the iron consumed, the iron may stain the poop green, the color of iron (II) salts. Ordinarily, the green color may be masked by the normal brown poop color, but if digestion is thrown off by illness so that bilirubin is less concentrated in the intestine, the green color may become apparent. This can happen when a person is afflicted with diarrhea.
Green poop in sick babies may come from iron in baby formula not being properly absorbed, or by green pigments in bile salts (again, green from iron).

Why is bird poop white?

Unlike mammals, birds don't urinate. Their kidneys extract nitrogenous wastes from the bloodstream, but instead of excreting it as urea dissolved in urine as we do, they excrete it in the form of uric acid. Uric acid has a very low solubility in water, so it emerges as a white paste. This material, as well as the output of the intestines, emerges from the bird's cloaca. The cloaca is a multi-purpose hole for birds: their wastes come out of it, they have sex by putting their cloacas together, and females lay eggs out of it.

Why do dogs (and other animals) eat poop?

Many animals eat poop on a regular basis. These include rabbits, rodents, gorillas, many insects such as dung beetles and flies, and yes, dogs. (Keep that in mind the next time a dog wants to lick you!) Herbivores such as rabbits and rodents eat their own poop because their diet of plants is hard to digest efficiently, and they have to make two passes at it to get everything out of the meal. This is equivalent to a cow chewing its cud, only cows are able to re-eat their food without having to poop it out first. Another reason why animals eat poop is that poop contains vitamins produced by their intestinal bacteria. The animal is unable to absorb the vitamins through the intestinal wall, but can get at them by eating the poop. Another reason that animals such as dogs and flies eat poop is that poop contains a certain amount of protein. Dogs are particularly fond of cat poop because cat poop is high in protein. I had a friend with a dog and a cat, and he never had to clean the kitty litter. The dog took care of it.

What causes diarrhea?

Diarrhea is caused by irritation in the intestines, resulting in the bowel passing its contents too fast for the water to be absorbed. There can be several causes, including infection by bacteria or viruses, irritation caused by unfamiliar foods, food allergies, chronic illnesses such as inflammatory bowel disease, lactose intolerance, medications, and nervousness. If it's a persistant problem, don't mess around - see a doctor.

How does poop stay together, like in links?

In humans, soft poop is really one long, mostly continuous sausage before it comes out. It gets its "link" look because we tend to pinch off lengths of it with the anal sphincter as the poop emerges. If a person pinches hard enough, the poop separates into several turd units. If the person doesn't pinch that hard, the turds may stay connected.
If you can remain sufficiently relaxed, you can produce an awesomely long poop that will coil up inside the toilet.

Why does some poop float?

Floaters are turds that have an unusually high gas content. Sometimes the gases produced by bacteria in our gut don't have a chance to collect into a large fart bubble, but remain dispersed in the feces. The poop then comes out foamy, and has a lower density than water. Poop with a high fat content will also float.

What causes the burning sensation sometimes associated with poop?

This is generally caused by a recent meal of hot peppers or related spices. The oils associated with these foods remain intact and active all the way through one's gastrointestinal system. These oils can also generate hot farts.

Why does some poop hurt when it comes out?

Turds can get very large and dry if a person is constipated, causing painful stretching of the anal opening. Pooping can also hurt if the person has hemorrhoids. Hemorrhoids are engorged veins in the anal area. A doctor once described them to me as "varicose veins of the anus," which suggests that the valves in the veins that are supposed to keep the blood flowing in the right direction have gotten messed up. Pooping can also be painful if the person suffers from an anal fissure, a tear in the tissue of the rectum.

Is it possible for a man to have poop come out of his penis, or for a woman to poop out of her vaginal opening?

Not normally; fortunately the plumbing of the genitalia is entirely separate from the plumbing of the digestive system! However, there are certain pathological situations that can cause the pipes to get connected together wrong. Cancer can do it, as can surgical diversions of the human tubing. Such fistulas, as they are called, can cause feces to come out of the urinary system, or urine to come out of the anus.

Credits hugely go to Scoop on Poop
'Types of Poops' to Aliensoup , Pecanpip
Image from Asiasoft Forum