# Node JS Package Manager - NPM

Node Package Manager (NPM) provides two main functionalities -

-   Online repositories for node.js packages/modules which are searchable on search.nodejs.org
-   Command line utility to install Node.js packages, do version management and dependency management of Node.js packages.

[NPM](https://www.npmjs.com/) comes bundled with Node.js installables after `v0.6.3` version. To verify the same, open console and type the following command and see the result -

```
npm --version
```

Installing Modules using NPM
----------------------------

```
// syntax
npm install <Module Name>
```

For example, following is the command to install a famous Node.js web framework module called `express` -

```
npm install express
```

Global vs Local Installation
----------------------------

By default, NPM installs any dependency in the local mode. Here local mode refers to the package installation in `node_modules` directory lying in the folder where Node application is present. Locally deployed packages are accessible via `require()` method. 

Now let's try installing the express module using local installation.

```
npm install express
```
**Globally** installed `packages/dependencies` are stored in system directory. Such dependencies can be used in `CLI` (Command Line Interface) function of any node.js but cannot be imported using require() in Node application directly. Now let's try installing the express module using global installation.

```
npm install express -g
```

Using package.json
------------------

`package.json` is present in the root directory of any Node application/module and is used to define the `information` of the current project and it contains list of `dependencies` present in your project.

As `node_modules/` folder contains packages and is not a part of code base so we don't share this folder along with the `source code` but this folder can be regenerate using package.json by using below command in the root directory of the project

```
npm install
```

OR

```
npm i
```

`In this section, we saw the learn about Node JS package manager and its Usage`