An HTML/XML developer creates and maintains web applications using HTML (HyperText Markup Language) and XML (eXtensible Markup Language). HTML is used to structure content on the web, while XML stores and transports data. The developer designs web page layout, integrates graphics and multimedia elements, and ensures the website is responsive and user-friendly. They also debug and troubleshoot coding issues, optimize applications for maximum speed and scalability, and ensure all web design is in compliance with industry standards. Additionally, they may work closely with other team members, such as graphic designers and UX designers, to create a seamless user experience.