Extreme Prototyping is employed mainly for web applications and usually in three phases:

• Static HTML/CSS/JS is created — this gives users an instant tangible feel for the product.
• Thereafter, the service layer is simulated — this includes business rules and logic.
• Lastly, the actual service layer is developed — this involves integrating with real-world systems and plugging that into the front end HTML/CSS/JS views.

This gives users an early view of the application without having actual functionality behind it. The backend will gradually come together as the process moves along.