Difference Between Coupling and Cohesion

Difference Between Coupling and Cohesion

5 mins read1.4K Views Comment
clickHere
Anshuman
Anshuman Singh
Senior Executive - Content
Updated on Mar 27, 2024 11:37 IST

In software engineering, Cohesion and Coupling are two important terminologies representing interconnection between different system parts. Most of us think both terms are the same, but it’s not the case. There are a lot of differences between coupling and cohesion.

2023_01_MicrosoftTeams-image-265.jpg

Are you aware of the difference between coupling and cohesion? If not, then don’t worry. In this article, we will discuss the difference between these terms (Coupling and Cohesion) in detail.

The main difference between coupling and cohesion is that coupling refers to the degree of interdependence between modules or components in a software system. In contrast, cohesion refers to the degree to which elements within a single module or component work together to achieve a single purpose.

You can also explore: Functional testing and its types

Before exploring the difference between coupling and cohesion in-depth, let’s go through the topics listed under the table of contents (TOC) we will cover in this article. Here’s the table of contents:

Table of Contents

Difference Between Coupling and Cohesion 

For a better understanding, let’s cover the difference between coupling and cohesion in a tabular format. 

Benchmark Coupling Cohesion
What is it? It refers to the degree of interdependence between modules or components in a software system. It refers to the degree to which elements within a single module or component work together to achieve a single purpose.
Also known as Inter-module Binding Intra-module Binding
It represents The relationships between modules or components. The relationship within a module or a component.
Created Between  two different modules. Between the same module.
The best software is produced when there is Loose coupling High cohesion
An increase in Coupling is avoided for software. Cohesion is good for software.

What is Coupling?

Coupling refers to the degree of interdependence between modules or components in a software system.

The high coupling means a module or component is highly dependent on others, while low coupling means it is more independent. The goal is to have low coupling, which allows for greater flexibility and maintainability in the software system. In layman’s terms, coupling represents the relationships between modules or components.

You can also explore: Feasibility study in software engineering

There are six types of coupling. Let’s explore each of them.

Coupling Type Description
Common coupling This type of coupling occurs when two or more modules share the same global data.
External coupling This type of coupling occurs when a software module interacts with elements outside of its control and can change independently, such as other software systems, user interfaces, etc.
Control coupling This type of coupling occurs when one module controls the execution of another.
Stamp coupling This type of coupling occurs when a module requires a specific implementation of another module.
Data coupling This type of coupling occurs when modules share data through parameters or return values.
Content coupling This type of coupling occurs when a module directly accesses the data of another module.

What is Cohesion?

Cohesion refers to the degree to which elements within a single module or component work together to achieve a single purpose.

High cohesion means elements are tightly related and work together to achieve a specific goal. Whereas low cohesion means elements are loosely related and do not have a clear purpose. The goal is high cohesion, leading to more modular and maintainable software systems. In layman’s terms, cohesion represents the relationship within a module or a component.

You can also explore: Acceptance testing with real-life examples

There are six types of cohesion. Let’s explore each of them.

Cohesion Type Description
Functional cohesion This type of cohesion occurs when all elements within a module are related to a single, well-defined function.
Procedural cohesion This type of cohesion occurs when elements within a module are organized as a series of steps to achieve a function.
Temporal cohesion This type of cohesion occurs when elements within a module are related by the time they are executed.
Sequential cohesion This type of cohesion occurs when elements within a module are organized in a specific sequence to achieve a function.
Layer cohesion This type of cohesion occurs when all the elements within a single layer are related to a single purpose and work together to achieve that purpose.
Communication cohesion This type of cohesion occurs when elements within a module are related by the data they manipulate.
Feasibility Study in Software Engineering
Feasibility Study in Software Engineering
A feasibility study, is designed to reveal whether a project/plan is feasible. In this article we will study about Feasibility study in software engineering and it also includes feasibility report...read more
Acceptance Testing with Real-life Examples
Acceptance Testing with Real-life Examples
Acceptance testing is formal testing based on user requirements and functional processing. Determine whether the software meets specified requirements and user requirements. This article revolves around Acceptance testing with real-life...read more
Functional testing and its types
Functional testing and its types
Functional testing is used to verify the functionality of the software application, whether the function is working according to the requirement specification.In this article we will focus on Functional testing...read more

Key Differences Between Coupling and Cohesion 

Here are the key differences between coupling and cohesion:

  • Coupling is also known as “Inter-module Binding.” In contrast, cohesion is known as “Intra-module Binding.”
  • An increase in coupling is avoided for software. At the same time, an increase in cohesion is good for software.
  • Cohesion is created between the same module. In comparison, the coupling is created between two different modules.
  • The best software is produced when there is loose coupling. In contrast, high cohesion is required to produce the best software.
  • Coupling represents the relationships between modules or components. But, cohesion represents the relationship within a module or a component.
  • During cohesion, the goal is high cohesion, leading to more modular and maintainable software systems. But, while coupling, the goal is to have low coupling, which allows for greater flexibility and maintainability in the software system.
  • Coupling refers to the degree of interdependence between modules or components in a software system. Whereas cohesion refers to the degree to which elements within a single module or component work together to achieve a single purpose.

You can also explore: Difference between Black box and White box testing

Conclusion

In simple terms, we can say that the main difference between coupling and cohesion is that coupling is about how much one component depends on others. Whereas, cohesion is about how well the elements within one component work together.

FAQs

How can high coupling and low cohesion impact software maintenance?

High coupling between modules makes it difficult to make changes or updates to one module without affecting other modules. Low cohesion within a module means its responsibilities are not well-organized, making it harder to understand and modify. Together, high coupling and low cohesion can significantly increase the effort and cost of software maintenance.

What design principles or patterns can help achieve loose coupling and high cohesion?

Some principles and patterns that promote loose coupling and high cohesion include the Single Responsibility Principle (SRP), the Interface Segregation Principle (ISP), the Dependency Inversion Principle (DIP), and the use of design patterns like Facade, Observer, and Strategy patterns.

How do coupling and cohesion relate to software quality attributes like reusability and testability?

Loosely coupled modules with high cohesion are more likely to be reusable, as they are independent and focused on a single responsibility. They are also easier to test in isolation due to their well-defined interfaces and limited dependencies.

About the Author
author-image
Anshuman Singh
Senior Executive - Content

Anshuman Singh is an accomplished content writer with over three years of experience specializing in cybersecurity, cloud computing, networking, and software testing. Known for his clear, concise, and informative wr... Read Full Bio