UML diagram
Definition
A UML (Unified Modeling Language) diagram is a standardized visual representation of a software system's structure or behavior, defined by the Object Management Group (OMG) and used across software engineering for design, documentation, and communication.
UML was created in the 1990s by Grady Booch, Ivar Jacobson, and James Rumbaugh — the 'three amigos' — as a unified notation that could replace the dozens of competing object-oriented modeling languages. The OMG adopted UML 1.0 in 1997; version 2.x is the current standard.
UML defines two broad categories:
Structure diagrams show what a system is. Class diagrams show objects and their relationships. Component diagrams show software modules. Deployment diagrams show where code runs in production.
Behavior diagrams show what a system does. Use case diagrams show what users can do. Sequence diagrams show how objects interact over time. Activity diagrams are flowcharts for object-oriented behavior. State machine diagrams show how an object transitions between states.
In practice, the diagrams teams draw most on whiteboards are class diagrams, sequence diagrams, and activity diagrams — and they're almost always informal approximations of strict UML rather than spec-compliant diagrams. That's fine: the value is in the shared vocabulary, not the notation compliance. BoardSnap AI reads whatever notation appears on the board and produces a structured summary of the design intent.
Examples
- Class diagram: User class with attributes (id, email, name) and methods (login(), logout()), connected to Order via 'places' association
- Sequence diagram: User → AuthService → TokenStore → User showing a login flow
- Use case diagram: Actor 'Customer' connected to 'Browse products,' 'Add to cart,' and 'Checkout' use cases
- State machine: Order states (Pending → Paid → Shipped → Delivered → Returned) with trigger labels
Snap a uml diagram. Ship its actions.
BoardSnap turns any whiteboard — including this one — into a summary and action plan.