 The mucous layer is an essential component of the intestine's first line of defense against pathogens. It consists of multiple layers of cells and proteins that work together to protect the body from harmful bacteria and other invaders. Recent research has revealed that the mucous layer is much more complex than previously thought, consisting of several different types of cells and proteins that interact with each other to create a strong barrier. Additionally, certain components of the mucous layer have been found to play a role in regulating its structure and function. These findings suggest that a better understanding of the mucous layer could lead to improved treatments for intestinal diseases like inflammatory bowel disease and colorectal cancer. This article was authored by Chun Yang Song, Jing Long Chai, Sai Chen, and others.