To help you organize your entries in related groups, you can assign categories to events, to-dos and journal entries. If you assign categories, you can use them later when searching, filtering, and displaying events and to-dos.
To assign categories when editing or creating new events or to-dos, select a category from the drop down box labelled Categories in the General tab. You can assign more than one category for each item.
To create, delete and edit categories, choose the → menu item to open the Edit Categories dialog. If you assign different colors to categories, you will be able to quickly identify the type of event by its color, either in the Agenda view or in the Month view (depending on the KOrganizer view configuration).