AnalysisJune 6, 2026· 8 min· 3 340
Use case diagram in simple words: guide and examples
What a use case diagram is, what it contains and how to build one for a product or online store.
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A use case diagram shows who can do what in a system. It is a map of product capabilities that non-technical people can also understand.
Main parts
- Actor: who interacts with the system
- Use case: what the actor does
- System boundary: where the product starts and ends
- Links: which actor uses which capability
Example: online store
Actors can be Buyer, Admin and Payment Service. Buyer use cases include search product, add to cart, place order, pay and track delivery.
Why it helps
The diagram prevents missing roles and scenarios. It also helps align scope before development starts.
Tip
AI SDLC can generate use case diagrams from requirements and update them when requirements change.
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