JavaScript is a programming language that is used to make websites interactive. You can use it to add text or graphics to a page, validate forms or to create navigation bars or other dynamic features.
It can be time-consuming to create certain elements using simple HTML and CSS, but with JavaScript you can create them almost instantly. For example, if you want a navigation bar that changes image when you hover over it, you can’t do this with CSS. You will have to use JavaScript.
JavaScript is also fun to use, and most websites you visit use JavaScript to display their content in the way they want.