While your digestive cells are absorbing sugars, starches, fats, vitamins, minerals, and other nutrients, waste products continue travelling down the line. In the colon, all the leftovers are combined, packed together, and partially dehydrated. What remains is our faeces which consist of water, indigestible fibre, undigested food such as corn and small seeds, sloughed-off dead cells, living and dead bacteria, intestinal secretions, and bile. The worn-out red blood cells in bile give excrement its distinctive brown colour.
If all goes as it should, you'll end up with a healthy bowel movement. Although digestive idiosyncrasies, variations in intestinal bacteria, and other variables can produce different standards for a healthy stool, in general it should be brown to light brown; formed but not hard; cylindrical, not flattened; fairly bulky and full-bodied, not compacted; somewhat textured but not too messy; and very easy to pass. And it shouldn't smell - much. You're passing methane and bacterial, degraded foodstuffs, so there's always going to be an odour, but it shouldn't be a very strong, pungent odour.
Experts disagree on two other stool characteristics the number of pieces and their buoyancy.
Some state that each bowel movement preferably should be in one piece, about the shape and size of a banana and tapered at the end. While others suggest stools don't have to be well-formed logs. They can disperse in the toilet water, in other words, they can break down.
On buoyancy, the opinion differs again. Some think stools should float because buoyancy is a sign that the body has absorbed the minerals in the food and that these nutrients are not contained in the waste. Whereas other say stools should sink because of their bulk and fibre content. However most stools will sink. And many scientists believe whether it floats or sinks really doesn't have any effect on your health.
An occasional deviation from this total picture is usually considered fine however chronic deviations or any featuring blood are not, and should be checked with a doctor.