A full stack developer works on both the front end and back end of a web application. Front end: What users see and interact with such as layouts, buttons, forms and navigation. The back end deals with server side things, databases, apis, authentication and application logic. A full stack developer can work with technologies like HTML, CSS, JavaScript, programming frameworks, databases, and server environments. They can be involved in the process of development, from the designing of user interfaces to creating server functionality, and even linking databases. Full stack developers are important because they have a firm grasp on the functionality of each part of the web application and can participate in many phases of development.