From CSE330 Wiki
MERN is a set of Open Source components that together, provide an end-to-end framework for building dynamic web applications; starting from the front-end (presentation layer) to the back-end (data access layer). The stack is made up of:
- Express.js: Back-end web application framework running on top of Node.js. Express can handle the routing of requests to the right parts of your applicatioN (or to different apps running in the same environment). You can run the app's full business logic within Express and even generate the final HTML to be rendered by the user's browser. At the other extreme, Express can be used to simply provide a REST API – giving the front-end app access to the resources it needs e.g., the database. For more information, please go here.
- MongoDB: Document database – used by your back-end application to store its data as JSON documents. MongoDB is an open-source, document database that provides persistence for your application data and is designed with both scalability and developer agility in mind. MongoDB bridges the gap between key-value stores, which are fast and scalable, and relational databases, which have rich functionality. Instead of storing data in rows and columns as one would with a relational database, MongoDB stores JSON documents in collections with dynamic schemas.