When designing a new application or making revisions to an
existing application, there is no substitute for the direct experience that end
users have. An end user can give immediate feedback on your design to point out
awkward or incorrect functionality. They also help to ensure that all controls
are logically placed for the most efficient use of the system.
Using an interactive prototyping tool allows you to walk a
user through the interface or even allow them to work directly with the
prototype so they can quickly suggest improvements. As use cases are being
developed, it is a good idea to walk users through the use case to ensure that
the use case is well thought out and that all functionality is captured both in
the use case and the prototype.