Express.js

Express.js is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs. It has become the standard server framework for Node.js.

The most frequently used fields for Express.js are:

1. Routing: Express.js provides a robust set of features for routing requests and providing responses.
2. Middleware: Express.js provides a large collection of middleware to handle requests and responses.
3. Templating: Express.js provides a powerful templating engine to help you quickly create dynamic webpages.

Technology related to Express.js includes web servers such as Nginx and Apache, databases such as MongoDB and MySQL, and web development frameworks such as React and Angular. Express.js is also used in combination with other technologies such as Socket.io for real-time communication and GraphQL for data querying.