Optical pulses are flashes of light, which are often generated with lasers (laser pulses) and delivered in the form of laser beams. Due to the enormously high optical frequencies, optical pulses can be extremely short (ultrashort) when their optical bandwidth spans a significant fraction of the mean frequency. Pulsed operation of lasers refers to any laser not classified as continuous wave, so that the optical power appears in pulses of some duration at some repetition rate. This encompasses a wide range of technologies addressing a number of different motivations. Some lasers are pulsed simply because they cannot be run in continuous mode. In other cases the application requires the production of pulses having as large an energy as possible. Since the pulse energy is equal to the average power divided by the repetition rate, this goal can sometimes be satisfied by lowering the rate of pulses so that more energy can be built up in between pulses. In laser ablation for example, a small volume of material at the surface of a work piece can be evaporated if it is heated in a very short time, whereas supplying the energy gradually would allow for the heat to be absorbed into the bulk of the piece, never attaining a sufficiently high temperature at a particular point. Other applications rely on the peak pulse power (rather than the energy in the pulse), especially in order to obtain nonlinear optical effects. For a given pulse energy, this requires creating pulses of the shortest possible duration utilising techniques such as Q-switching. This book discusses aspects of laser pulses generation, characterisation, and practical applications. Some new achievements in theory, experiments, and design are demonstrated. This book will be useful for engineers and managers, for professors and students, and for those who are interested in laser science and technologies.