MERN Stack is a powerful JavaScript-based technology stack used for building modern, dynamic, and scalable web applications. It consists of MongoDB (NoSQL database), Express.js (backend framework), React (front-end library), and Node.js (runtime environment), allowing developers to work seamlessly across the entire development process using a single language—JavaScript. With its flexibility, efficiency, and high demand in the industry, mastering MERN Stack opens doors to exciting career opportunities in full-stack web development.