Giving the right feedback when something fails to happen in an app is just as important as showing content. Craig Dennis of Codrops has taken a look at what sits in the empty spaces of frequently used apps — the empty inbox of Sparrow, the failed page load of Safari, or the blank Favorites page of Dropbox. The first order of business is clarity: it should be easy to tell whether there's been an error or if there's simply nothing to show, a test that Apple's default mail app fails. The message designers choose will also determine whether users are alarmed, confused, or reassured. For designers, it's a guide to how different apps are perceived; for everyone else, it's a look behind how the people who create your apps are thinking about putting you at ease.