What Is UML Diagram: Types & Features

What Is UML Diagram

One of the most common ways of presenting an in-depth visual representation for engineering and software development is Unified Modeling Language, also known as UML. Ideally, UML diagrams are correlated with OOP languages like JAVA and C++. 

It supports us in providing an overall software structure and the flow of instructions. Different UML diagrams can be drawn under all sorts of situations. This guide will help you learn about the different types of UML diagrams and why one should need UML diagrams. But before we move onto its types, let us discuss first what is UML diagram.

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What Is UML Diagram?

UML is the short form of Unified Modelling Language. It is a standardized, general-purpose modeling language that is mainly applied for creating object-oriented, meaningful documentation models for any software system present in the real world. The Unified Modelling Language consists of a set of graphic notation techniques to create visual models. It gives us the means to develop strong models that represent software/hardware systems’ working. It can be used with all processes during the software development lifecycle and different technologies.

UML normally has two types of diagrams which we are going to discuss below but before that let us discuss UML’s features. 

Features of UML

  • Unified Modeling Language is a generalized modeling language.
  • It is not the same as other software programming languages such as C, C++, Python.
  • UML is a pictorial language that can be applied to create powerful modeling elements.
  • It is similar to object-oriented designs and analysis.
  • It has extensive applications even outside the software industry. It is also used to reflect the workflow of a company.

Types of UML Diagram

There are usually three types of UML diagrams which we are going to discuss in the below section but before that let us try to understand a glimpse of it through the diagram.

Types of UML diagram

Structural diagrams

Structural diagrams represent a structure or static view of a system. It is extensively used in software architecture documentation. It includes class diagrams, component diagrams, composite structure diagrams, object diagrams, deployment diagrams, and package diagrams. It gives an outline for the system. Following are the different types of structural diagrams in UML:

  • Class diagram
  • Package diagram
  • Object diagram
  • Deployment diagram
  • Component diagram
  • Composite Structure Diagram

Class Diagram:  

It represents the system’s static structure. It helps understand the relationship between various objects and classes.

Object Diagram: 

It describes different examples of classes and the relationship between them at a time. It is also used to examine the efficiency of class diagrams. 

Composite Structure Diagram:  

It displays the connection between the parts and their arrangement that determines the behavior of the class. It makes full use of parts, ports, and connectors to describe the inner structure of a structured classifier. 

Deployment Diagram:

It provides information regarding system software. It is included whenever software is used, distributed, or extended across various machines with various configurations.

Component Diagram:

It decides whether the development has estimated the desired functional conditions or not, as it describes the structural relation between the software system’s elements.

Package Diagram:

It is utilized to explain how the packages and their elements are made. It shows the dependencies between different packages.

Behavioral diagrams

Behavioral diagrams describe a system’s dynamic view or behavior, which represents the system’s functioning. It involves state diagrams, use case diagrams, and activity diagrams. It describes the interaction in the system.

Following are the different types of behavioral diagrams in UML:

  • Activity diagram
  • Use case diagram
  • State machine diagram
  • Interaction Diagrams

State Machine Diagram: 

Also known as the State-charts diagram. It shows the dynamic class behavior in response to outer stimuli.

Activity Diagram: 

Using an activity diagram, we can create regular and concurrent activities. It visually describes the workflow as well as what makes an event happen.

Use Case Diagram: 

It describes the system’s functionality by using use cases and actors. It encapsulates the functional necessity of a system and its relationship with actors. 

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Interaction diagrams

These diagrams are the parts of behavioral diagrams that indicate object interactions and describe the flow between different system’s use case elements. In easy words, it explains how objects communicate with each other and how the data flows inside them. It consists of:

  • Sequence Diagram
  • Communication Diagram
  • Timing Diagram
  • Interaction Overview diagram

Conceptual model

Before we start the UML concept, you need to understand the fundamentals of the conceptual model.

A conceptual model is built up of several interrelated concepts. It helps us to understand what objects are and How interaction takes place to perform a process. In UML, A conceptual model is required. You need to know the entities and relations between them before modeling the system. Following object-oriented theories are needed to start with UML:

  • Object: It is a real-world entity. There are many objects possible in a single system. It is a basic building block of Unified Modelling Language.
  • Class: It is nothing but a vessel where objects and relations are kept.
  • Abstraction: It is a way of representing an object without exposing the implementation details. It is utilized to reflect the presence of an object.
  • Inheritance: It is a mechanism of increasing an actual class to produce a different class.
  • Polymorphism: It represents an object having various forms that are utilized for various purposes.
  • Encapsulation: It is a way of connecting data and objects data together as one unit. It guarantees a strong connection between the data and the object.

Unified Modelling Language Tools

For generating UML diagrams there are several tools available in the market today. Few are desktop-based while many of them can be utilized online. Following is a list of tools that you can use for creating UML models:

  • Dia
  • UML lab
  • Enterprise Architect
  • Star UML
  • Argo UML
  • Visual Paradigm
  • U-Model

Why Do We Need UML?

  • A complicated business application with several associates will need a firm foundation of planning and clear, concise communication between team members as the project proceeds.
  • Understanding codes are not easy for business people. UML plays a crucial role here and becomes necessary to interact with non-programmers’ fundamental requirements, functionalities, and methods.
  • A lot of time is saved when teams can visualize processes, user interactions, and the system’s static structure.

UML is associated with object-oriented design and analysis. Unified Modelling Language makes the use of elements and forms relationships between them.

How To Make A UML Diagram

Here are some steps on how to make a UML diagram:

Step 1: Identify the System

Determine the system’s purpose and its components. Understand what needs to be represented in the diagram, like classes, interactions, or processes.

Step 2: Select the UML Diagram Type

Choose the appropriate UML diagram type for your system. Decide if it’s a class diagram, use case diagram, sequence diagram, etc., based on what you want to illustrate.

Step 3: Gather Information

Collect relevant details about the system elements. This includes attributes, relationships, behaviors, and constraints among the components.

Step 4: Create the Diagram

Use a UML diagram tool or software to build the diagram. Place the elements (classes, actors, objects) and establish connections based on the gathered information.

Step 5: Review and Refine

Check for accuracy and completeness. Ensure the diagram clearly represents the system and its functionalities. Refine it if needed for better clarity or detail.


I hope after reading this blog you have a clear picture of what is UML diagram and the different types of UML diagrams out there. Since UML is still evolving, its standards keep changing over time. Whenever you want to create an awesome UML diagram, you can take our UML Diagram help. You will get more information regarding diagrams and their standard symbols.

Frequently Asked Questions

Q 1. What is the significance of UML diagrams in software development?

UML diagrams serve as a visual representation, aiding communication among stakeholders and developers. They depict system architecture, behaviour, relationships, and design patterns, facilitating better understanding, planning, and efficient development processes.

Q 2. How many types of UML diagrams are commonly used in software engineering?

Commonly used UML diagrams include Class diagrams, Use Case diagrams, Sequence diagrams, Activity diagrams, and others. Each type serves a specific purpose, such as depicting structure, behaviour, interactions, or flow within a system.

Q 3. Can UML diagrams be used beyond software development?

Yes, UML’s visual modeling technique finds application beyond software. It’s employed in various fields like business process modeling, system engineering, and even in non-software domains to represent structures, interactions, and processes for better understanding and planning.