The peritoneum is a thin membrane that lines the abdominal cavity and covers the organs within it, such as the stomach, liver, and intestines. It plays a crucial role in protecting these organs and providing a smooth surface that allows them to move freely during digestion. This membrane consists of two layers: the parietal peritoneum, which lines the abdominal wall, and the visceral peritoneum, which envelops the organs. The peritoneum also produces a small amount of fluid that helps reduce friction between the organs, facilitating their movement and function.