HTML is the markup language used to define the way a website's content appears to the user. It is responsible for the back-end code that is read by the web browser to create the front-end of the website. Back-end refers to the driving force of a website and includes the HTML and CSS code processed by the broswer. CSS is a coding language used to establish a library of visual styles used throughtout the website and is responsible for the presentation of a website. JavaScript is a scripting language that allows one to programme events that happen when the user performs certain actions.