Decide Whether an Interaction Should Be Obvious, Easy, or Possible

While we strive to make our products as intuitive and familiar as possible, there will always be “advanced” options and rarely used features (see #32, Categorize Settings in an Accessible Way). Giving users choice and control over their experience will naturally lead to features that are used less frequently or settings that only a small percentage of users will change.

To help decide where (and how prominently) a control or interaction should be placed, it’s useful to classify interactions into one of three types:

• Obvious: Obvious interactions are the core function of an app, for example, the shutter button on a camera app or the new event button on a calendar app. They’re the functions that users will likely perform every time they use your product and their controls should be visible and intuitive. Hiding these away—either accidentally or intentionally—does...