Microorganisms are among the main causes of disease, but most of us know very little about what they do and how they infect us and grow. These creatures are microscopic but they can make us very sick and even kill us. Discover the range of natural and technological defences we have against them, and why we can never let our guard down when they are around.

STEM stands for science, technology, engineering and mathematics, and it is not just for scientists. The existence of the whole Universe, including us and our daily lives, can all be described with the wonderful scientific facts that make up the topics included in STEM. In this series, you will find out how easy STEM is to understand, and also discover how you can see it in action every second of every day.