Optimistic updates (also known as optimistic UI) are when the UI updates immediately as if an operation succeeded, before the backend actually confirms it. It is a strategy used to makes web apps feel snappier, when it in fact deceives the user. Imagine seeing a confirmation message that an action succeeded, only to be shown a second later that it actually failed. Rather than deceive the user, use loading indicators to show the user that the action is in progress, and only confirm success from the backend.