Types of UML Diagrams

The current UML standards call for 14 different kinds of diagrams.
These diagrams are organized into two distinct groups:

• structural diagrams and
• behavioral or interaction diagrams.

As the names suggest, some UML diagrams analyze and depict the structure of a system or process, whereas others describe the behavior of the system, its actors, and its building components.

The different types are broken down as follows:

Structural UML diagrams

1. Class diagram
2. Object diagram
3. Package diagram
4. Component diagram
5. Composite structure diagram
6. Deployment diagram
7. Profile diagram

Behavioral UML diagrams

1. Use case diagram
2. Activity diagram
3. Sequence diagram
4. State diagram
5. Communication diagram
6. Interaction overview diagram
7. Timing diagram

Well the most commonly is debatable, but the must known for anyone should be:

• Use Case Diagram: Used to describe a set of user scenarios, this diagram, illustrates the functionality provided by the system.

• Class Diagram: Used to describe structure and behavior in the use cases, this diagram provides a conceptual model of the system in terms of entities and their relationships.

• Activity Diagram: Used to model the functional flow-of-control between two or more class objects.

• Sequence Diagram: Used to describe interactions among classes in terms of an exchange of messages over time.