Bilirubin, a pigment derived from the breakdown of red blood cells, exists in two main forms: free bilirubin, and after being processed by the liver, conjugated bilirubin. Conjugated bilirubin is excreted in the bile, is degraded in the small intestine and colon, and evacuated in the stool. It is these degradation products that give the stool its brown color. Jaundice is a yellow coloring of the skin in relation to the increase of bilirubin. Jaundice is usually due to increased levels of free bilirubin in the blood, but certain rare forms of jaundice of genetic origin are connected with conjugated bilirubin.