HTML is a formatting language, not a programming language. Javascript is often necessary to make HTML “dynamic.” While HTML can make it so that text is displayed on the screen, Javascript can update this text or make it move. Javascript is used for both front-end and back-end development, hand-in-hand with HTML, to create complex and attractive web designs. Meanwhile, CSS (Cascading Style Sheets) are used to organize the look and feel of a website and make the website easier to update and manipulate. Today, HTML, CSS, and Javascript are frequently used to develop responsive web designs — designs that react to a user’s environment for a better user experience.