What is Node.js?

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.

Node.js is an open source, cross-platform runtime environment for server-side and networking applications. Node.js applications are written in JavaScript and can be run within the Node.js runtime on OS X, Microsoft Windows, Linux, FreeBSD, NonStop, IBM AIX, IBM System z and IBM i. Its work is hosted and supported by the Node.js Foundation, a Collaborative Project at Linux Foundation. Node.js provides an event-driven architecture and a non-blocking I/O API that optimizes an application's throughput and scalability. These technologies are commonly used for real-time web applications.

Node.js uses the Google V8 JavaScript engine to execute code, and a large percentage of the basic modules are written in JavaScript. Node.js contains a built-in library to allow applications to act as a Web server without software such as Apache HTTP Server or IIS. Node.js is gaining adoption as a server-side platform and is used by IBM, Microsoft, Yahoo!, Walmart, Groupon, SAP, LinkedIn, Rakuten, PayPal, Voxer, and GoDaddy.

Node.js was invented in 2009 by Ryan Dahl, and other developers working at Joyent. Node.js was created and first published for Linux use in 2009. Its development and maintenance was spearheaded by Ryan Dahl and sponsored by Joyent, the firm where Dahl worked.

Node.js allows the creation of web servers and networking tools, using JavaScript and a collection of "modules" that handle various core functionality. Modules handle file system I/O, networking (HTTP, TCP, UDP, DNS, or TLS/SSL), binary data (buffers), cryptography functions, data streams, and other core functions. Node's modules have a simple and elegant API, reducing the complexity of writing server applications.

Frameworks can be used to accelerate the development of applications, and common frameworks are Express.js, Socket.IO and Connect. Node.js applications can run on Microsoft Windows, Unix and Mac OS X servers. Node.js applications can alternatively be written with CoffeeScript (a more readable form of JavaScript), Dart or Microsoft TypeScript (strongly typed forms of JavaScript), or any language that can compile to JavaScript.