Let's say you've built a MERN stack application, which means you've got MongoDB for your database, Express and Node.js for the server-side, and React for the frontend. Now, you want to run this application on another computer or server. Traditionally, you'd have to install MongoDB, set up Express and Node.js, and configure everything manually. It can be time-consuming and prone to errors. But with Docker, you don't need to go through all that hassle again. Instead, you can package your entire MERN stack application into a Docker Container. This container will have MongoDB, Express, Node.js and your React frontend all set up and ready to go. So, when you want to deploy your application on a different device, you simply take this Docker container and run it. Everything you need to run your MERN stack application is already inside the container. It's like a self-contained package that you can easily move around and deploy wherever you need, ensuring that your application runs consistently and smoothly on any device.