What are the five steps for requirements analysis with Use Case Diagrams?

Question

Accepted Answer

Context model → Glossary → Detail the context model → Scenarios (sequence diagrams) → Activity diagrams — zooming from "who touches the system" down to "exactly how each flow runs".
The order is deliberate: you start at the widest zoom (every actor and the system as one box) and progressively add detail, so you never dive into a flow before you've agreed who's even involved:
Step-by-step breakdown:

Step
Action
Purpose

1
Draw context model
Show system and all actors

2
Write glossary
Define terms consistently

3
Detail context model
Expand with specific use cases

4
Define scenarios
Use sequence diagrams for flows

5
Use activity diagrams
Generalize behavior patterns

For Security: Add a sixth step - Add Misuse Cases to identify security threats and their mitigations.

Step	Action	Purpose
1	Draw context model	Show system and all actors
2	Write glossary	Define terms consistently
3	Detail context model	Expand with specific use cases
4	Define scenarios	Use sequence diagrams for flows
5	Use activity diagrams	Generalize behavior patterns