On the fast growing market of precision micro-machining of metals lasers do not only compete with other methods of structuring. There is also strong competition among different laser-processing strategies and, especially, among laser sources with different pulse duration. A comprehensive study of laser micro-machining with nanosecond, picosecond, and femtosecond laser pulses will be presented with a focus on fundamental aspects of the processes and on their practical consequences. An analysis will be given of the potential or the limitations of these laser processes with respect to their industrial application.