To create a simple backend to store data, we use the Express framework. This is a very simple Node.js backend framework, which allows us to create a simple backend quickly. To store data, we will use an SQLite database to keep the project simple. We will use the Express framework to create an API to enable the frontend to make HTTP requests to it. We let them make requests by exposing the API endpoint, which the frontend can use by adding routes into it. Each route has a handler function that handles the data submitted by the frontend. We get request data from the HTTP requests made by the frontend, which includes the headers and the body, and we use them in the route handlers to get and store the data the way we want.