In addition to organizing, viewing and editing your events, KOrganizer also provides alarm notification for the events. If you like, KOrganizer reminds you of upcoming events.
This happens by a simple popup window, by playing a sound file or starting a user-defined program and is configurable on an event-by-event basis.
You can also suspend alarms and run the alarm notification without running the complete KOrganizer application. This will place a small icon in the system tray of your KDE control panel.