Node.js is becoming increasingly popular with developers, it has become mainstream enough to be featured in a recent .Net magazine .. but what is it?
Basically node.js is another back-end or server-side technology (sort of like using Ruby or Python and not very much like PHP - but you get the general location) and it's used to create web applications.
It is an event-driven input/output framework which means it's suited to applications that run off events such as online user interactions.
The main benefits are that it has fast performance and can scale to support a larger number of users/events on the same hardware as current web server systems.
As mentioned on the Node.js site "..less-than-expert programmers are able to develop fast systems."
If you're a Developer and what to know more then the following resources are a great start:
or check out these slides from a presentation of a beginners guide to Node.js