At the dawn of the second quantum century, physicist Alexey Semikhatov offers a coherent account of the current state of quantum mechanics. What are the fundamental features of the quantum world, and at what cost can they be reconciled with intuition? By what rules do quantum systems evolve over time, and how do probabilities intervene in this development? How do various interpretations of quantum mechanics prompt us to deeply philosophical conclusions about the possible structure of reality—from parallel universes to discontinuities in perception? And how does our familiar reality emerge from the alien quantum reality? It turns out that quantum mechanics can be discussed seriously and in understandable terms, and discussing its complexities only makes the conversation more engaging.