Bacteria and viruses have lived on this planet long before us, and for a long time they posed no serious danger to humans. What has changed, and how does micro-life on Earth work today? In his book, Yuri Chirkov, Doctor of Chemical Sciences and popularizer of scientific knowledge, explains the nature, origins, and behavioral features of the tiniest organisms inhabiting the planet. You will find fascinating chapters about scientists of the past and their discoveries in the fields of microbiology, virology, and immunology. Learn how and why the first epidemics occurred, how our internal microbiome and immune system work, why viruses can be so deadly, and whether bacteria can become our friends.