MERN is an abbreviation that stands for MongoDB, Express, React, and Node.js, a collection of web application development tools. It adopts three-tier architecture. Hence expanding the application is possible as the requirements change. MERN is popular among developers who wants to develop application quickly.

MongoDB is a NoSQL database with high scalability and flexibility. Hence unstructured data can be stored and managed using JSON format.

Express is a Node.js web framework that helps developers rapidly and effectively create APIs and online apps. It also has many inbuilt features and tools that help in developing server-side applications.