Software architecture is the set of structures needed to reason about a software system and the discipline of creating such structures and systems. Each structure comprises software elements, relations among them, and properties of both elements and relations.
Software architecture activities
A view model or viewpoints framework in systems engineering, software engineering, and enterprise engineering is a framework which defines a coherent set of views to be used in the construction of a system architecture, software architecture, or enterprise architecture. A view is a representation of the whole system from the perspective of a related set of concerns.
Simplified illustration of the Zachman Framework with an explanation of the rows. The original framework is more advanced, see for an example here.
The RM-ODP view model, which provides five generic and complementary viewpoints on the system and its environment.
DoDAF linkages among views.
Federal Enterprise Architecture levels and attributes