Cows have only one stomach, but it is divided into four distinct compartments, which are:
Rumen - the first section of the cow's stomach, which aids in the breakdown of complex plant foods such as grass.
Reticulum - This is where the food combines with the saliva of the cow to produce cud. Cows burp up the cud and chew it to help break it down further.
Omasum - This is where all of the water from the food is absorbed.
Abomasum - This is the final stage of digestion, similar to what happens in the human stomach.