The Omentum is a layer of fat that is covered by the peritoneum. It is in two parts, the greater omentum and the less omentum. The greater omentum is attached to the bottom edge of the stomach, and hangs down in front of the intestines. Its other edge is attached to the transverse colon. The lesser omentum is attached to the top edge of the stomach, and extends to the undersurface of the liver.
We don’t know why it has evolved as part of the human body, but it does reach every organ in the abdomen. In particular it drapes over and attaches itself to any areas of inflammation a little like a bandage might be used on the outer body and limbs. Therefore it is possible that it may help to reduce the spread of infection in the abdomen.