Bacteria are so minuscule you can only see them under a microscope. They come in different types, shapes and sizes and are single-cell organisms that can multiply on their own. They live virtually everywhere on, in and around us. You can find them in soil, water, and air They also reside all over our skin, and inside the nose, mouth, throat, digestive tract, and vagina.

They're not all bad, though. In fact, out of the estimated one nonillion bacteria on earth, very few are harmful to us (relatively speaking). There are good bacteria that protect us from harmful bacteria by preventing them from multiplying and keeping them at bay. Good gut bacteria protect your digestive tract from invading pathogens, and a proliferation of bad bacteria. They help to repair damaged tissue in your gut lining, destroy disease-causing microbes and aid nutrient absorption.

Good bacteria can also fight cancer cells and may help to speed up the healing of external wounds.