Why is Urine yellow?? :) :O

Question: Why is Urine yellow?? :) :O
- Keywords:
  body function,
  human body,
  urine,
  yellow
Asked by sas6 to Daphne, Darren, Jon, Katherine on 21 Mar 2012. This question was also asked by bambi.
- Daphne Ng answered on 21 Mar 2012:
  
  Urine is yellow because of urobilin which is a product from the breakdown of hemoglobin, the oxygen binding protein in red blood cells. Pale yellow urine indicates that the person is well hydrated e.g. consumed enough water whereas dark yellow urine indicates dehydration.

Question: Why is Urine yellow?? :) :O