Confirming and acknowledging actions can help alleviate uncertainty about things that have happened or will happen. It also prevents users from making mistakes they might regret.
Not all actions warrant a confirmation or an acknowledgment.
A confirmation asks the user to verify that they truly want to proceed with the action they just invoked. It may be paired with a warning or critical information related to that action.
Modal dialog titles for confirmations should be meaningful and echo the requested action.
Confirmation isn’t necessary when the consequences of an action are reversible or negligible. For example, if a check mark shows an image has been selected, further confirmation is unnecessary.
The user has requested to delete an album from their library. An alert appears to confirm this action and inform the user that the album will no longer be available from any device.
After initiating Android Beam, the user is prompted to touch the content to be shared. If they decide not to proceed, they simply move their phone away.
Acknowledgement removes uncertainty about implicit operations that the system is taking. It may be paired with an option to undo the action.
The draft of an email is saved if the user navigates back or up from the compose screen. An acknowledgment in the form of a toast appears, then fades after a few seconds.
After the user deletes a conversation from the list view, an acknowledgment appears with an undo option. It remains until the user takes an unrelated action, such as scrolling the list.