Extreme Prototyping as a development process is used especially for developing web applications. Basically, it breaks down web development into three phases, each one based on the preceding one. The first phase is a static prototype that consists mainly of HTML pages. In the second phase, the screens are programmed and fully functional using a simulated services layer. In the third phase, the services are implemented. The process is called Extreme Prototyping to draw attention to the second phase of the process, where a fully functional UI is developed with very little regard to the services other than their contract.