Frontend developers are developers of the UI of websites and applications through the use of HTML, CSS and JavaScript which allow users to interact with sites and apps. For eg. When we enter the URL and press enter then the page opens in the front end. In short, what the user can see is the front end

The backend developer is responsible for server-side web application logic and integration of the work that comes from front end developer. They are also responsible for taking decisions, data sanitization and processing.