MERN stands for MongoDB, Express, React and Node, after the four key technologies that make up the stack. MongoDB (a document database), Express.js (a Node.js web framework), React.js (a client-side JavaScript framework) and Node.js (the premier JavaScript web server).

The combination means that JSON data flows naturally from front to back, making it fast to build on and reasonably simple to debug. Plus, you only have to know one programming language, and the JSON document structure, to understand the whole system. MERN is the stack of choice for todays web developers looking to move quickly, particularly for those with React.js experience. Like any web stack, you can build whatever you want in MERN, though it's ideally suited for cases that are JSON heavy, cloud-native, and that have dynamic web interfaces. A few examples might be. Workflow management, news aggregation, to-do apps and calendars, interactive forums, or social products. And whatever else you can dream up.