Examples are the context diagram and use case diagrams. Such models are very useful strategically. They complement product visions, stories, or value propositions, customer segmentations, customer personae, etc. Also, they can be progressively elaborated into more detailed structural and/or dynamic models.

Here is a fine video – 8 minutes or so – on four such models; 1) the context diagram, 2) the use case diagram, 3) the feature roadmap, and 4) system events. The focus here is on the context diagram, by way of a detailed example.