UML Diagram Types and Templates

Looking for a quick rundown of UML diagram types? Welcome to Gliffy. We're here to help. We've even got UML diagram templates to get you started.

Types of UML Diagrams

There are, as of UML 2.5, fourteen officially recognized types of UML diagrams. These types get sorted into three buckets:

• Structure diagrams,
• Behavioral diagrams, and
• Interaction diagrams (sometimes considered a subset of behavior diagrams)

In this article, we’ll briefly explain the different UML diagram types and illustrate each with an example. Each example is also a dynamic template you can use to create your own UML diagrams.

To launch any one in Gliffy, just click on it. You can access all these templates, plus more, by opening Gliffy, selecting ‘New’ from the File menu, and expanding ‘Software Design & UML’ from the list.

UML Structure Diagram Types

Structure diagrams depict the static elements of your application (its parts and how they relate).

Class Diagrams

Class diagrams use classes and interfaces to depict a system’s structure. They provide an overview of the project as seen as a collection of static elements.

Object Diagrams

Object diagrams are akin to class diagrams, only drilled down to the instance-specific level. They’re like a snapshot of the system’s structure taken at a specific point of operation. In the example below the variables of the above class diagram are specified to match the object instance.

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Package Diagrams

Package diagrams show system elements split into packages connected by inter-package relationships. They’re class diagrams with a level of compartmentalization added to help designers minimize dependencies.

Composite Structure Diagrams

There are two types of composite structure diagrams:

• Internal structure diagrams, which break classifiers down into properties, parts, and relationships; and
• Collaboration use diagrams, which show how system objects cooperate to produce a combined behavior within the system.

Component Diagrams

Component diagrams illustrate how the components in a system link up to form that system.

Deployment Diagrams

Deployment diagrams map out the physical deployment of artifacts (software components) on nodes (hardware components), so you can see which pieces of software live on which pieces of hardware and how those artifacts on nodes interrelate.

Profile Diagrams

Profile diagrams extend UML by allowing you to define stereotypes, tagged values, and constraints as a means of adapting the UML metamodel for different domains and platforms. Profile diagrams are abstract by design; they help you abstract elements in UML for use in other areas.

UML Behavioral Diagram Types

Behavioral (or behavior) and interaction diagrams illustrate different aspects of your system’s dynamic functionality—how the objects in the system change over time.

Use Case Diagrams

Use case diagrams depict how users interact with a system through use cases that produce observable results. Use case diagrams are, in simple terms, about functionality; i.e. if one does this using the system, then this is the result.

Activity Diagrams

Activity diagrams are UML’s version of the flowchart. They illustrate workflow as a sequence of activities and actions, revealing how control flows dynamically through a system in response to operations performed on classes in the system.

State Machine Diagrams

State machine diagrams model system behavior over a number of transitions so that the designer can see the singular ‘state’ of the system at any point given the indicated external stimuli.

UML Interaction Diagram Types

Sequence Diagrams

Sequence diagrams show how distinct processes operate in conjunction over time. They map out the exchange of messages between subsystems (such as a computer and server) as the diagrammed scenario unfolds.

Communication Diagrams

Communication diagrams (aka collaboration diagrams) are interaction diagrams that center on architecture and how internal structure corresponds to the passing of messages.

Timing Diagrams

Timing diagramsare sequence diagrams that focus on how objects behave over defined increments of time. In timing diagrams, time is plotted along the horizontal axis in specified units so you can see what is meant to occur in the 4th millisecond, minute, or month of operation.

Interaction Overview Diagrams

Interaction overview diagrams combine the activity diagram type with that of an interaction diagram so that a sequence of activities gets broken into discrete activities. Each activity gets compartmentalized within a frame, which in turn contains an interaction diagram or diagrams. This form helps to distill complex scenarios so they can be depicted in a single, comprehensible diagram.

And those are the fourteen officially recognized UML diagram types! Collect the whole set and you’ll be the envy of your peers, assuming your peers are software developers.

If want a quick lesson on how to create UML diagrams using Gliffy, we’ve got you covered.

Ready to jump in and get drawing? Use templates or start from scratch in Gliffy Online — we're loaded with tools specifically to make diagramming easy for software developers.

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