App designers are professionals who create the layout and user experience of mobile applications. They focus on how the app looks and feels, ensuring it is visually appealing and easy to navigate. Their work involves using design software and tools to develop prototypes and mockups that represent the final product. These designers often collaborate with developers and product managers to understand user needs and technical requirements. They conduct user research and testing to gather feedback, which helps them refine the app's design. Ultimately, app designers play a crucial role in making applications user-friendly and engaging.