Explore the fascinating world of quantum chaos in this Infosys Prize Lecture delivered by Nalini Anantharaman. Delve into the historical context of quantum mechanics, starting from Bohr's model of the hydrogen atom and Einstein's early contributions. Examine the development of quantum ergodicity and its applications to various systems, including billiards and graphs. Investigate the Quantum Unique Ergodicity conjecture and recent theoretical advancements. Gain insights into toy models, regular graphs, and their relevance to quantum chaos. Discover numerical simulations, deterministic and random results, and engage with open questions in this cutting-edge field of physics. Conclude with a thought-provoking Q&A session to further expand your understanding of quantum chaos and its implications.