A Microsoft Windows NT service responsible for sending administrative alerts to users and computers. The Alerter service generates an alert when potentially dangerous conditions occur, such as when disk space is running out. You can configure which users or computers receive these alerts by using Server Manager (or by using the Server utility in Control Panel).
Pop-up alert messages will appear if the administrator is logged on or is at the appropriate computer when the alert occurs. The administrator can then consult the system log for information about what caused the alert.