Gives a clear picture of how your ideas and proposed features will fuse together into a functional app.
Gives an opportunity to evaluate design concepts, gather feedback, and identify dead links and flaws in the flow and usability of the app .
The designer architects the interaction between design elements, and builds the look and feel of the app.
Involves a number of steps each involving a chunk of functionality incorporated in the app .
Starts as soon as the first feature is implemented. Test ,and test again to sniff out and correct any technical flaws.