Our age is marked by great technological, socio-cultural and ecological changes. Modern highly efficient technologies bring us up to date with current knowledge about the world and challenge us to develop new concepts of life. These include the new findings about the microbiome, which completely redefine what it means to be human. The many connections between humans and microorganisms are the focus of this issue of Home Delivery. What is the microbiome? How do you make the microbiome visible and what does a healthy meal have to do with our microbiome? We address these and many other questions in an entertaining and easy-to-understand way.