I will describe the contents and theme of my Oxford University Press 2018 book of the above title. The book reviews the past half‐century of research, primarily in particle and nuclear physics and cosmology, bearing on the physical conditions needed to arrive at a universe containing structure capable of supporting life. That research has clarified the essential role of imperfections ‐‐ deviations from perfect symmetry or homogeneity or predictability ‐‐ many of which are tiny and seem mysteriously fine‐tuned to allow for life. My emphasis is on the intricate tapestry of elegant experiments that have revealed and quantified these imperfections, in other words, on what we know and how we know it, as distinct from what we speculate and how we might test it. I will also indicate the most important open questions regarding the early universe, including the philosophical one of whether such a finely tuned universe is a product of chance, design, immutable laws of physics, or an unknown optimization algorithm for universe evolution.