The bacteria living in our intestinal tract, the gut microbiota, play a key role in our health. It accomplishes different functions and stimulates the development and maintenance of the intestinal immune system that protects us from being affected by environmental pathogens that sometimes enter the body. A video animation released by Nature featuring the expertise of world-renowned immunologist Tom MacDonald from the University of London, shows the key cells and molecular players involved in this mechanism. You realise how amazing the human body is!!