Developed medicine saves the lives of millions of people, but its downside - the abuse of technology and drugs - again puts our health at risk. The obesity epidemic affects up to 30% of Americans; The number of children with autoimmune diabetes in Finland has increased by 550% over half a century of antibiotic use. Dr. Martin Blaser has been studying the human microbiome - bacteria living with us in symbiosis - for more than 30 years and knows for sure: resistant strains that cause fatal diseases, an increase in diseases in children and such ailments of developed countries as asthma, allergies, obesity, diabetes, some forms of cancer, arise due to a violation of the microbiome. In order to protect children and not become part of the sad statistics, you need to know: how pathogenic bacteria differ from beneficial ones and what benefits we get from symbiosis with the latter; exactly how antibiotics undermine our health and in what cases their use is justified; what threatens our microflora and how to restore it, and with it, health.