The gallbladder stores bile produced by the liver to be used by the stomach later for food digestion. It sides just cranial to the stomach in a small hole within the right medial lobe of the liver and the quadrate lobe.

In this picture the gallbladder is clearly labeled

NOTE: the mesentery tissue labeled in this picture is incorrect; not only is mesentery spelled wrong but that is greater omentum!!!liver_lobes.jpg