Information Functionality: How Breadcrumbs, Site Maps And Site Navigation Are The Critical Conversion-Rate Drivers
"A fascinating thing about watching visitors navigate is recognizing that repeat visitors typically use sites differently than first-time visitors. You might consider changing your navigation based on this, as Amazon.com changes the tabs displayed based on purchase and browsing patterns. As Don Norman of the Nielsen Norman Group said, "Usability is not the goal. Honest, it isn't. Usability is always secondary. The goal is to satisfy the needs of the user. Although some forms of navigation may be more useful than others, each has the potential to drive sales. None should be neglected."
