TypeScript uses a module system to organize code into reusable and maintainable units. The module system in TypeScript is a powerful feature that allows you to structure your code, promote separation of concerns, and manage dependencies. Here's an overview of TypeScript's module system:

Modules vs. Namespaces:

• In TypeScript, there are two primary ways to encapsulate code: modules and namespaces.
• Modules are used for organizing code into separate files, and they provide a way to manage dependencies and keep related code together.
• Namespaces, on the other hand, are used for organizing code within a single file and are mainly used when working with older TypeScript or JavaScript code.

Module Files:

• A TypeScript module can be a single file with a .ts extension. Each module typically contains a cohesive set of related code, such as classes, functions, or variables.
• Modules are defined using the export keyword to make code accessible from outside the module.

Module Resolution:

• TypeScript employs module resolution to locate and load modules. The resolution process is based on a specified module resolution strategy or configuration.
• Common module resolution strategies include Node.js modules ("node"), CommonJS ("commonjs"), and ES modules ("esnext").

Module Resolution Paths:

• You can configure module resolution paths in the tsconfig.json file, making it easier to manage module dependencies. This allows you to specify where TypeScript should look for modules.

Circular Dependencies:

• TypeScript can handle circular dependencies, but it's a good practice to refactor your code to avoid them, as they can make code harder to understand and maintain.

External Modules:

• TypeScript supports external modules, which are designed for code reuse and distribution. External modules are typically bundled using tools like Webpack or Rollup.

Type Declarations:

• TypeScript supports type declaration files (.d.ts) that allow you to provide type information for external JavaScript libraries and modules that don't have TypeScript support.

In summary, TypeScript's module system is a powerful way to structure code, manage dependencies, and promote code organization. It facilitates code separation, reusability, and maintainability, making it an essential feature for developing large-scale TypeScript applications.