Your peritoneum is a multiple layered serous membrane that lines the abdominal cavity. Its inner layer is referred to as the visceral peritoneum, which wraps around most of your abdominal organs. But does not encase them all. Parietal peritoneum is the outer layer, which attach to the wall of the abdomen.
Inflammation of your peritoneum is known as peritonitis. And cancer can develop in this membrane, yet it rarely does.
The space between the peritoneum layers is called the peritoneal cavity. Normally, it is filled with a small amount of serous fluid. This fluid acts as a lubricant and is slippery, so the layers can slide freely past one another.