In Apple's iOS, a badge app icon is a small, changeable modification of an application's icon. These attention-getting visual notifications feature a number that appears at the top right corner of the app icon in white text against a red background.
Badge app icons provide information about potentially important activity on an iPhone. For instance, when new e-mail messages arrive, the number on the mail application's badge changes to represent the current number of unread messages in the inbox. Missed phone calls and voicemails cause the badge app icon of the phone app to register a number. Users who don't want to see badge app icons may toggle these notifications on or off using the notification center subsection of the settings app.