What are the processes (grouping of activities) involved in engineering a system?
Complex systems engineering

Engineering is the upstream part of development, i.e. the definition and creation/design of the system with a view to realizing a future product, service or organization. Engineering activities are divided into generic processes, each dealing with a specific theme (see figure below). The engineering processes contain the mechanisms for identifying and developing, in a controlled way, the maturity of the definition and design of the system under study.

You use them iteratively and concurrently, because the partial result of an activity in one process enables you to start or continue an activity in another process, until you have a complete and coherent set of engineering data for your system.