A systems engineering methodology is a collection of related processes, methods, and tools that support the discipline of systems engineering in a specific context. The activities in a typical systems engineering methodology are applied iteratively, meaning that they are repeated and refined until a satisfactory solution is achieved. The activities are not applied sequentially, meaning that they are not performed in a fixed order without revisiting previous steps. The activities cannot be performed in any order, because they have logical dependencies and prerequisites. The activities do not work just as well for specialty engineering activities, because they may require different processes, methods, and tools