If you've ever had a cold or the flu, you know firsthand that microbes can make you sick. But did you know that you have trillions of harmless bacteria living inside you right now? This collection is known as the "microbiome" and it plays important roles in digestion, helping our immune systems develop, and fending off invading pathogens. We'll talk about symbiotic microbes in nature - like the glowing bacterium Vibrio fischeri that lives inside a Hawaiian squid. Then we'll take a look at our own microbes and learn how we study them in the lab. For more focus on human microbes take "Healthy Bacteria" with Tyler!