$ionicBackdrop performs shows and hides backdrop over UI. Appears behind popups, loading, and other overlays. Usually multiple UI components require a backdrop but only one backdrop is needed in DOM. Each component which requires backdrop to be shown calls $ionicVackdrop.retain() when it wants to backdrop then $ionicBackdrop.release() when it is done with the backdrop. Method $ionicBackdrop.retain() and $ionicBackdrop.release() is used for backdrop. $ionicBackdrop.retain() is used to apply overlay over the content. $ionicBackdrop.release() is used to remove Ionic Backdrop from content. Each time when $ionicBackdrop.retain() is called $ionicBackdrop.release() method is called.