Definitions

Affordances: "The perceived and actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used."4 Affordances are the nonverbal language of control, the physical cues that tell users how things operate. "If a push-button is placed on the wall next to the front door of a residence, its affordances are 100% doorbell."5 A site affords its users few usable cues when text is underlined on a page but is not a link, or when the user can't tell the difference between linked and unlinked graphics.

Behavioral consistency: Words, situations, or actions that mean the same thing throughout a system. A navigation bar that appears in the same place with the same choices on every page of a site is behaviorally consistent. A button graphic that serves as a link on one page and a decorative element on another page is not behaviorally consistent. Performing a certain action should always have the same result throughout a site. Page elements should appear consistently in the same places throughout a site.

Population stereotype: Intuitive expectations held by most users about the way things will work. On old radio tuners, turning the knob clockwise moved the pointer to the right. There's no particular reason why it should, but everyone came to expect it. Work with the population stereotype wherever possible - for instance, the 'next' button should appear to the right of the 'back' button.