UI-Fullstack refers to a development approach where professionals build entire web applications, encompassing both the user interface (UI) and the underlying backend logic and infrastructure. This means they are proficient in front-end technologies like HTML, CSS, and JavaScript, as well as back-end technologies like Node.js, databases (SQL and NoSQL), and API development. Full-stack UI developers create user-friendly and visually appealing interfaces while also handling the server-side logic and data management.