Everything in our world depends on bacteria. For a long time—almost 4 billion years—the Earth was at their complete disposal. It was these microscopic engines of life that changed the chemical composition of our planet and made the world habitable for plants, animals and people. Where did these amazing microorganisms come from? How do they work and what secrets do they hide? Why is life impossible without them? And why are bacteria social organisms? The famous American biologist-oceanographer Paul Falkowski, a member of the American Geophysical Union, the American Academy of Arts and Sciences, tells how and why bacteria were able to survive all the cataclysms and adapt to a changing environment, and also demonstrates to the reader that everything is ours existence became possible only thanks to their evolution, and they are our true ancestors and the real engines of life on Earth.