When should prototyping begin within an application development process?

Prototyping should begin after class structures and data models are stable because this stage ensures that there is a solid foundation for the user interface to build upon. A well-defined data model and class structure allow developers to create prototypes that accurately reflect how the application is intended to function. This makes it easier to gather user feedback, make adjustments, and ultimately refine the user experience based on real data needs and user interactions.

During prototyping, it’s essential to have a clear understanding of the underlying data and functionalities that the user interface will represent. If these elements are not stable, the prototype may lead to confusion or misalignment with the application’s core functionalities and goals. This phase is critical to iteratively test design concepts and get early feedback on usability and design without committing to a final version, ultimately guiding the development process more effectively.

Starting prototyping at other stages, such as when the user interface is finalized or after testing is completed, would likely result in less effective prototypes that do not align with the application's purpose, potentially wasting resources and time.