The starting point and quasi unifying bracket of all process models is the life cycle model shown in Fig. 3.1 (e.g. Naefe 2018, p. 13 ff.; Thommen and Achleitner 2006, p. 60 f.; Wiendahl 2014, p. 99 f.). This describes the observation that all systems are virtually born, grow up, live for a while and finally die. This does not happen in a linear fashion, but in definable phases. There are recognizable transitions from one phase to the next. The first transition is birth. This is followed by a phase of development in which systems still have to develop their full potential. The duration and subject of this development can vary greatly from system to system: while humans, for example, need around a year to learn to walk, flight animals in particular succeed in doing so just a few minutes after birth. And the development of an airplane differs considerably from that of a rice stove, not only in terms of duration but also in terms of content. However, the basic course of the life cycles is always largely comparable.