Tiny creatures are constantly crawling through your body. But don’t panic! These little guys belong to you. Bacteria, fungi, yeasts, viruses, and other single-celled creatures are constantly inside you. And that's a good thing. Without them, life would be a lot more difficult! Together, all of these organisms make up your microbiome. The most important ones are found in your gut, and they can be both good and bad. Intestinal bacteria ensure that your intestines contract, keep your intestinal wall thick and strong, and train your immune system to protect you against harmful substances. This keeps your microbiome in balance. Without balance, your whole body gets upset!