Viruses aren't like anything else you can see under a microscope. Is a virus a living thing or something else? Readers explore the answer to this question as they examine viruses, learning what they look like and how they affect us. As readers discover important facts about how viruses multiply and what sicknesses they cause, they expand their knowledge of essential parts of science curricula, including beginner biology concepts. In addition to the informative narrative, fun fact boxes, vibrant, full-color photographs, and a creative design hold readers' interest as they learn more about this important topic.