If the front-end is what users see, the back-end is what they don’t. Back-end web developers work on the servers of websites, programs, and software to make sure everything works properly behind-the-scenes.
These developers work in systems like servers, operating systems, and databases and manage the code for security, content, and site structure. They collaborate with front-end developers to bring their products to users.
So far, what you have is an example of a static website — its content doesn’t really change much. For static sites, all the necessary information that determines what’s on the web page is in the frontend code itself. Static websites are good for showcasing things like businesses, restaurants, or professional profiles. But if you want to turn your site into something that users can interact with, you’ll need to get more in-depth with regard to what’s going on behind the scenes of the website.
The backend (or “server-side”) is the portion of the website you don’t see. It’s responsible for storing and organizing data, and ensuring everything on the client-side actually works. The backend communicates with the front-end, sending and receiving information to be displayed as a web page. Whenever you fill out a contact form, type in a web address, or make a purchase (any user interaction on the client-side), your browser sends a request to the server-side, which returns information in the form of frontend code that the browser can interpret and display.
Your new site will need to have additional backend components to make it a dynamic web application — a website whose content can change based on what is in its database, and that can be modified by user input. This is distinct from a static website, which doesn’t require a database because its content generally stays the same.