NodeJS

Node.js is an open-source program for running JavaScript code on the server-side.

We will be running many commands from Node, including the server that will run our game later this week! When you download Node, you won't find an application that you can open from your desktop, instead we'll be issuing instructions to our computer via the command line - but just because you can't see it doesn't mean it isn't there, you'll have to trust me on this one for now.

Get it from nodejs.org.