When getting started with Node JS you may hear the term NPM being used often (usually lowercase 'npm'). What exactly is it and how can you use it?
Well... npm stands for Node Package Manager and it is an online repository for open source Node.JS projects. This repository is used to store and retrieve Node Packages, such as SocketIO, RequireJS, and many other open source Node projects. You can search through the directory at: http://search.npmjs.org/
Adding a node package to your node project is as simple as opening up a terminal command, navigating to a directory, and then typing 'npm install package_name'. You'll have to install node which includes the npm utility from the official NodeJS website at: http://nodejs.org. So, for instance if you want to install the SocketIO package you would simply type 'npm install socket.io' in a terminal window. You can checkout their documentation of how to use it at: http://socket.io/#how-to-use.
Node is an amazing library and in order to take advantage of all it's greatness you'll usually be using a node package alongside it. The Node Package Manager repository keeps all the open source projects up-to-date which gives you access to the latest and greatest Node packages. Checkout the NPM site at: http://www.npmjs.org.