Module

A module is a self-contained part of a program that handles one specific responsibility.

Think of it as a small box inside your application:

Application
│
├── Auth Module
├── User Module
├── Task Module
└── Notification Module

Each module contains the code needed for its particular feature.

Example

Suppose you have a task manager.

The Task module might contain:

tasks/
├── task.controller.js
├── task.service.js
├── task.routes.js
└── task.validation.js

Together, these files form the Task module.

It might be responsible for:

• creating tasks

• deleting tasks

• updating tasks

• getting tasks

• validating task data

Why call it a “module”?

Because you can think about it independently:

Task Module
     ↓
"Everything related to tasks"

instead of having task-related code scattered throughout the entire application.

Module vs file

They’re not necessarily the same thing.

A file is one source-code file:

task.service.js

A module is a logical unit of functionality and can contain one or many files:

tasks/
├── task.controller.js
├── task.service.js
├── task.routes.js
└── task.validation.js
        ↑
   Task module

So the easiest definition is:

A module is a self-contained piece of an application that groups code belonging to one functionality or responsibility.

And modular architecture simply means building the application out of these modules.

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