Abstract: The history of the birth of quantum physics is overviewed. Quantum physics has opened the door to our understanding of macroscopic matter at the microscopic level. The properties and microscopic structure of matter can only be accounted for within the frame of quantum physics, and indeed, quantum physics underpins the fundamentals of all modern science. As quantum physics celebrates its 100th birthday, spectacular successes are accompanied with persistent puzzles. On the one hand, quantum physics has not only interpreted a variety of scientific phenomena but has also brought about immense breakthroughs in technology. On the other hand, the basic concepts of quantum physics are still sometimes regarded as being at odds with “common sense”, and there have been ongoing debates on its very foundations since its birth. Quantum theory has been and will always challenge our view of nature and the universe.