Express is a minimal and flexible node.js web application framework, providing a robust
set of features for building single and multi-page, and hybrid web applications.
What do we mean by minimal yet flexible and powerful?
Express is minimal because it does not come loaded with all sorts of functionality,
which makes it a bloat-free framework. Out of the box, it supports only the very
basic features of a web framework. Even the supported features are not all enabled
by default, you have the option to pick and use, according to your needs.
Express.js is based on the Connect middleware engine: Any Connect-specific middleware
will also work with Express. Besides allowing you to set up middleware to respond to HTTP
requests, Express.js allows you perform different actions based on the HTTP method and
URL — by letting you defi ne a routing table. It also allows you to dynamically render HTML
documents based on supplying arguments to templates.
More information on Express : Express.JS