How could I have missed that?
node.js is an evented I/O for Google V8 engine.
Okay, so what does that mean?
Basically it means it is a library on top of V8 that enables you to do things with JavaScript that haven’t been possible before. Things like coding and running your own webserver or tcp server. As nodejs never stops running processes it can do several things at the same time. Like running the webserver and doing calls to another webserver at the same time, for several users and without running more than one process.
To be honest it is easier if you just watch this video. It’s worth watching!