What is MERN Stack? How does it work?

What is MERN Stack? How does it work?

Today, we can’t imagine a world without the internet. It has kept us informed, and connected and made our life a lot easier. The internet is made up of web applications that we use almost every day. A website today should be fast, scalable, and easy to build, otherwise, it won’t be able to meet users’ needs.  MERN stack is one of the most popularly used collections of technologies for faster application development. It stands for MongoDB, Express.js, React.js, and Node.js. It is named after the four key technologies that make up the stack, which are:

  • M – MongoDB:  document database
  • E – ExpressJS: Node.js web framework
  • R – ReactJS: A client-side JavaScript framework
  • N – NodeJS: Premier JavaScript web server

One of the main reasons the MERN stack is popular is because the application is built with only one language i.e JavaScript. It solves the problem of implementing different languages at the front end and back end. Let’s take a look at the MERN stack in detail.


Frontend development involves building interactive and aesthetically pleasing websites. Working on the front end requires HTML, CSS, and JavaScript knowledge. Building scalable and concise code using conventional methods without any modern framework or libraries is a huge task. Here’s when frameworks and libraries started to boom and ReactJS is one such example. ReactJS is the most popular open-source, component-based front-end library in 2022. It is maintained by Facebook and has massive community support and makes front-end development very easy with its tools, performance, and scalability factors. We can build dynamic webpages using ReactJS much faster when compared to conventional vanilla JavaScript web development. 

Apart from being easier to code and understand, ReactJS enables developers to build single-page applications, i.e while shifting between different routes, the website won’t require a reload. It also allows us to create reusable UI components which save the developer from repetitive lengthy code.

Learning ReactJS is a must if you want to be a front-end developer in 2022. And now, frameworks are built on top of React js to improve its functionality like NextJS. Many libraries are also made specifically for ReactJS due to its overwhelming community base.  You can start your journey along here, and learn ReactJS with Codedamn’s interactive playgrounds.

NodeJS and ExpressJS

Previously, JavaScript was a client-side language and could only be used on the client side – that is, web browsers. But, with the release of Node.js in 2009, things changed. Node.js is an open-source, cross-platform, back-end JavaScript runtime environment. It runs on a JavaScript Engine and executes JavaScript code outside a web browser.

Nodejs helps us manage the servers and routes of our application. Now, the problem was that Node.js does not know how to perform serving files, handling requests, and handling HTTP methods. Here’s where express.js steps up.

Express JS is a Node.js framework designed to build API’s web applications cross-platform mobile apps quickly and make node js easy. Express provides many features such as routing, easier debugging, and middleware.

You can start learning about NodeJS and ExpressJS from here.


Last but not least, we have MongoDB. Since we have learned about the front-end and back-end technologies, let’s know what kind of database we’ll be using in this stack. Why do we need a database? A database is used to store information of the users visiting your website, for example creating an account, bank balance, student information, etc. The list could go on and on with its use cases. There are several databases in the market, so what makes MongoDB special? It is an open-source document NoSQL database. NoSQL database systems offer an alternative to traditional relational databases using SQL (Structured Query Language) like MySQL. The data is stored in tables, rows, and columns in a relational database, with relationships between entities. Whereas, in NoSQL databases such as MongoDB, the data is represented in a JSON-like structure which is stored in documents.

MongoDB stores data in an unstructured format and processes non-similar data sets that are associated with each other. Therefore, it has fewer restrictions and more flexibility with the use of dissimilar fields within a collection as compared to relational databases. Moreover, we can use MongoDB Atlas for a fully-managed cloud database for full-scale applications and we use the mongoose npm library to connect the database with our backend. You can learn how to connect and build applications with Node.js and MongoDB from the course here.


Since we learned about all the technologies that go into building up the MERN stack, let’s take a look at how they work together.

There is no specific order to start working on a MERN stack project. But usually, developers prefer to start with the backend development and make the schema for the application. We also establish a connection between our MongoDB database with our backend using the Mongoose library. 

With the help of express.js, we create APIs, which enable the developers to read, create, update and delete data from the database while constantly listening for server requests. We use these API URLs in our frontend React application to communicate the data with the backend. We perform different HTTP requests for different uses such as GET to read data, POST to create new data, DELETE to delete data from the database, and so on. The data is transferred in JSON format, also known as JavaScript Object Notation. The data stored in MongoDB is also in JSON format, which makes it easier to read and update.


MERN stack is a fully scalable web solution for modern needs. By learning the MERN stack you’ll be known as a full-stack developer. You’ll ideally be able to build and deploy medium to large-size applications end to end, from frontend to backend to databases.

Web development has been growing rapidly and new frameworks and libraries come and go every month. Getting to development is an ever-learning career, but once having core knowledge it doesn’t take much time to move on to another stack. Codedamn offers amazing courses at cheap prices that will make you a full-stack developer. Start learning and get your dream job as a full-stack developer here

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