I came up with a brainstorming app and I built it with MERN. Like MEAN but with React instead of Angular. 

MERN is an acronym that stands for MongoDB, Express.js, React, and Node.js. It refers to a popular stack of technologies used for building modern web applications. Each component of the MERN stack represents a different layer of the application's architecture and contributes to the overall development process.

Here's an overview of each technology in the MERN stack:

MongoDB: MongoDB is a NoSQL database that stores data in a flexible, JSON-like format called BSON. It is known for its scalability, flexibility, and ability to handle large volumes of data. MongoDB is often used to store the application's data and provides a convenient way to interact with structured and unstructured data.

Express.js: Express.js is a web application framework for Node.js. It simplifies the process of building robust and scalable server-side applications. Express.js provides a set of tools and middleware to handle routing, request handling, and other common tasks, making it easier to create APIs and handle server-side logic.

React: React is a JavaScript library for building user interfaces. It focuses on creating dynamic and interactive user interfaces by using a component-based approach. React allows developers to build reusable UI components that efficiently update and render based on changes in application state. It is commonly used for creating the client-side of web applications.

Node.js: Node.js is a server-side runtime environment that allows developers to build scalable and event-driven applications using JavaScript. Node.js provides a non-blocking, asynchronous architecture, making it well-suited for handling I/O-heavy tasks and building APIs.

When combined, the MERN stack allows developers to build full-stack web applications with a consistent JavaScript-based technology stack from front to back. Data flows seamlessly between the various components of the stack, enabling developers to create feature-rich and responsive web applications.

MERN is just one of many available technology stacks, and its popularity stems from the combination of powerful and modern technologies that work well together. It's worth noting that there are variations of the MERN stack, such as MEAN (which uses Angular instead of React) and MEVN (which uses Vue.js instead of React), providing developers with flexibility in choosing the front-end library or framework that best suits their needs.