With this ViewHelper you are able to set a block condition which is only shown if there is a frontend user logged in. In this case it does not matter to which usergroup the user belongs.
<f:security.ifAuthenticated> <f:then> This part is shown if there is a frontend user logged in. </f:then> <f:else> This part is shown if the current user is not logged in. </f:else> </f:security.ifAuthenticated>