Construction has several purposes: (1) create a hi-fi computer prototype, (2) further iterate your design and test with users and key stake-holders, and (3) document your complete, final design for the development team.

The objective of hi-fi computer prototyping is to have a detailed design of almost all windows and dialog boxes that can be used to conduct user testing.

• Create the Prototype: prototyping allows you to test and revise the actual screen layout.
• What is and is not a prototype: it is not critical that the prototyping perform data processing, but it should allow users to navigate within the interface and use graphical controls. The prototype doesn’t have to simulate the full functionality of the system.
• Prioritizing the Prototype: prototype high frequency tasks

After you develop the hi-fi computer prototype, someone is going to have to implement it in code. How do you communicate and document the entire interface design so that the development team knows how the interface should not only look, but also behave?

• Prototypes Alone are not Enough: spending time developing a fully complete system prototype for documentation purposes will discourage design iteration.
• The Problem with Typical Interface Documentation: system design documents often specified a user interface design using a combination of screen drawings or prints and flow charts. The problem is that these representations don’t work well for describing a GUI. Some designers have devised special notations and languages for the purpose of describing user interfaces.
• The User Interface Design Description: a UIDD documents your interface design. It describes the screen objects, and all interactions in detail for each window or screen.