What is the difference between Namespace and Module?

What You'll Learn

Namespaces (internal modules)
ES Modules (external modules)
When to use each

Namespaces

Legacy TypeScript pattern for organizing code.

code.tsTypeScript

namespace Validation {
  export interface Validator {
    validate(value: string): boolean;
  }

  export class EmailValidator implements Validator {
    validate(value: string): boolean {
      return value.includes("@");
    }
  }
}

const validator = new Validation.EmailValidator();

ES Modules (Preferred)

Standard JavaScript module system.

code.tsTypeScript

// validator.ts
export interface Validator {
  validate(value: string): boolean;
}

export class EmailValidator implements Validator {
  validate(value: string): boolean {
    return value.includes("@");
  }
}

// app.ts
import { EmailValidator } from "./validator";
const validator = new EmailValidator();

Comparison

Feature	Namespace	Module
Standard	TypeScript only	ES standard
File scope	No (global)	Yes
Tree-shaking	No	Yes
Modern bundlers	Limited	Full support

When to Use

Modules: Always for new code
Namespaces: Legacy code, ambient declarations