There are many causes of jaundice. The most common, obviously, is hepatitis. But also drugs, toxins, Gilbert's syndrome, sepsis, cancers, gallstones and other conditions can cause jaundice.
Jaundice is also the result of a failing liver. The yellow coloring is from too much bilirubin in the blood which the liver normally filters out. When something is wrong with the liver, it is unable to filter that out, thus causing the yellowing.