An alert is designed to notify you of a problem or to ask a question.
All alerts can be directional, meaning upon closing the alert, the user can go to a new screen, or be returned to the original screen.
You can have as many alerts on a screen as you want, however, you cannot have more than one of the same type of alert from the source to the target. For instance, you cannot have two error alerts from a source screen to a target screen, but you could have an error alert and a question alert from the source screen to the target screen.
Alerts are shown as connection arrows with the alert type in the middle of the connection line.