Expressjs

Express.js, commonly called Express, is a minimal and flexible web application framework for Node.js. It provides a robust set of features for building web applications and APIs, and is widely used in server-side development with Node.js.

Express builds on top of Node's HTTP module and offers a middleware-based architecture. Developers compose request-handling logic as a stack of middleware functions that have access to the request and response objects and can either respond to the client or pass control to the next middleware using next().

Routing is a core feature, with a simple API for defining routes for different HTTP methods (get, post, put, delete, etc.) and for configurable URL patterns. Express.Router enables modular routing by combining multiple route handlers into separate modules.

The framework provides convenience features such as static file serving via express.static, as well as view/template engine integration with popular engines like Pug, EJS, and Handlebars. It also supports common middleware for parsing request bodies, cookies, and sessions, either built-in (express.json, express.urlencoded) or via third-party packages.

Express's ecosystem includes a large collection of middleware and extensions available through npm, allowing developers to add authentication, logging, validation, error handling, and more without starting from scratch.

History and usage: Express was created by TJ Holowaychuk in 2010. It has grown into one of the most popular Node.js frameworks and is commonly used for building RESTful APIs, server-rendered web pages, and single-page applications in combination with frontend frameworks. Express is published on npm and installed with npm install express.