A Human Machine Interface (HMI) developer designs and implements interfaces that facilitate interaction between humans and machines. They create graphical displays of information that help users control and monitor automated systems. Their work involves understanding user needs, designing interface layouts, programming the interface's functionality, and testing its usability. They work closely with engineers and designers to ensure that the interface is intuitive and efficient. HMI developers also troubleshoot issues, provide technical support, and update the interface based on user feedback and technological advancements. Their ultimate goal is to enhance user experience and system performance.