Mockups are an essential part of the app development process. They provide a visual representation of the app's interface, helping to define its overall design and user experience before development begins. By using mockups, you can test out different design layouts, color schemes, and functionality in the early stages, which can ultimately help streamline the development process. They allow stakeholders, such as team members or clients, to give feedback before heavy investments are made. Additionally, mockups help identify potential usability issues, ensuring that the final product is intuitive and easy to navigate.