Abstract： Optical frequency combs are having a broad impact on science and technology by pushing metrology of time and frequency to the best accuracy. Integration of these systems on photonic chips would revolutionize the instrumentation as well as a wide range of subjects. Such miniaturized approach has been proposed in high-quality-factor (high-Q) microresonators and was recently leveraged by the demonstration of mode locking through the formation of light bullets called optical solitons. In this talk I will trace the development of soliton microcombs including their physical origins. I will also cover discoveries of novel nonlinear phenomena in soliton microcombs, followed by ground-breaking applications spanning spectroscopy and telecommunication to chip-based optical frequency synthesizers and atomic clocks.