It’s the “fit factor” that seem to drive the other two pillars. The value of any brand is its good name, which it earns over time. People become loyal to it; they trust it to deliver a consistent set of attributes. You can’t just take a familiar brand name and slap it on a product in another category. Instead, a good extension should fit logically with its parent brand. But brands are complex perceptual and emotional entities, so fit can be hard to define. One way to assure fit is to focus on the brand’s core product portfolio.