Our world is awash with germs, viruses, and bacteria—tiny but powerful invaders that can make us sick. Fortunately, the human immune system mounts an amazing defense against all these attackers. Immunology will introduce you to the many strategies our bodies use to protect us, as well as the many things that can go wrong. Each title in this series contains color photos throughout, and back matter including: an index and further reading lists for books and internet resources. Key Icons appear throughout the books in this series in an effort to encourage library readers to build knowledge, gain awareness, explore possibilities and expand their viewpoints through our content rich non-fiction books. Key Icons in this series are as follows: Words to Understand are shown at the front of each chapter with definitions. These words are set in boldfaced type in that chapter, so that readers are able to reference back to the definitions—building their vocabulary and enhancing their reading comprehension. Sidebars are highlighted graphics with content rich material within that allows readers to build knowledge and broaden their perspectives by weaving together additional information to provide realistic and holistic perspectives. Text Dependent Questions are placed at the end of each book. They challenge the reader's comprehension of the chapters they have just read, while sending the reader back to the text for more careful attention to the evidence presented there. Research Projects are provided at the end of each book as well and provide readers with suggestions for projects that encourage deeper research and analysis. Educational Videos are offered through the use of a QR code, that when scanned, takes the student to an online video showing a moment in history, speech etc. This gives the readers additional content to supplement the text.