Front-end developers are responsible for a website’s user-facing code and the architecture of its immersive user experiences. In order to execute those objectives, front-end devs must be adept at three main languages: HTML, CSS, and Javascript programming. In addition to fluency in these languages, front-end devs need to be familiar with frameworks like Bootstrap, Foundation, Backbone, AngularJS, and EmberJS, which ensure great-looking content no matter the device, and libraries like jQuery and LESS, which package code into a more useful, time-saving form. A lot of front-end developer job listings also call for experience with Ajax, a widely used technique for using Javascript that lets pages dynamically load by downloading server data in the background.