What exactly is node.js used for?
What can we build with NodeJS:
- REST APIs and Backend Applications
- Real-Time services (Chat, Games etc)
- Blogs, CMS, Social Applications.
- Utilities and Tools
- Anything that is not CPU intensive.
Directly from the node.js tag wiki, make sure watch some of the talk videos linked there to get a better idea.
Node.js is an event based, asynchronous I/O framework that uses Google's V8 JavaScript Engine.
Node.js - or just Node as it's commonly called - is used for developing applications that make heavy use of the ability to run JavaScript both on the client, as well as on server side and therefore benefit from the re-usability of code and the lack of context switching.
It's also possible to use matured JavaScript frameworks like YUI and jQuery for server side DOM manipulation.
To ease the development of complex JavaScript further, Node.js supports the CommonJS standard that allows for modularized development and the distribution of software in packages via the Node Package Manager.
Applications that can be written using Node.js include, but are not limited to:
- Static file servers
- Web Application frameworks
- Messaging middle ware
- Servers for HTML5 multi player games
From Node.js website
Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.
Event-driven means that the server only reacts when an event occurs. This allow us to create high performance, highly scalable, “real-time” applications.
Finally, this is probably the best article that will get you excited about Node.js
Node.js is a runtime that compiles and executes javaScript. It can be used to develop application that runs end-to-end in JavaScript i..e both client side and server side uses javascript code unlike most of todays' application with rich client framework (angularJs, extJs) and RESTful server side APIs