JavaScript is a programming language. It's hugely popular and almost every application you encounter will be powered by it.
It lets you do cool things like:
To follow the tutorials on this site, there are a few essential things you will need:
A web browser with good developer tools will save you hours and help you in development.
Chrome is our browser of choice, you can download this at https://www.google.com/chrome/
Visual studio is a free text editor which comes with lots of helpful features. You can install it from https://code.visualstudio.com/
If you're on a mac, the Treehouse blog has a very basic introduction to the command line
Follow the Treehouse tutorial on installing Node.js and NPM for mac.