Working models.
WHAT A WIREFRAME IS
A structural layout without visual detail.
WHAT IT IS FOR
Agreeing what goes where, before appearance is discussed.
WHAT A PROTOTYPE IS
Something clickable, demonstrating flow.
WHAT IT IS FOR
Testing whether people can complete a task, before anything is built.
WHY THAT MATTERS
Changing a prototype costs minutes. Changing built software costs days.
WHAT FIDELITY TO USE
The lowest that answers the question.
WHAT TO PROTOTYPE
The main path, and the parts you are uncertain about.
WHAT NOT TO PROTOTYPE
Everything.
WHAT TO TEST WITH IT
Real tasks, with real people.
WHAT TO USE FOR CONTENT
Realistic content, including long and awkward examples.
WHY NOT PLACEHOLDER TEXT
It hides every problem real content will cause.
WHAT TO AVOID
Prototypes so polished they are mistaken for finished work Spending longer prototyping than building would take