Tags
Tags are user-defined labels with which you can categorize and color events in BusyCal. You can also search and filter events in your calendar based on tags.
Note: Tags in BusyCal map to Categories in Exchange/Outlook.
Entering Tags
To apply tags to events, type them in the Tags field. When adding tags to an event, the tags are auto-completed as you type, based on tags you have entered previously.

Note: To see the Tags field on the Info Panel, you must enable it in Info Panel Preferences.
You can also apply tags to an event by Control-clicking an event and choosing a tag from the contextual menu.

Tag History
BusyCal automatically remembers tags as you create them and adds them to the Tag History. Choose Edit > Edit Tags to open the Tag History dialog, where you can add, delete, rename, and colorize tags.

Note: Deleting or renaming a tag in the Tag History dialog does not affect any events that already have that tag applied. However, changing the color of a tag does affect all events with that tag.
Tag Colors
You can use tags to color events. For example, you can have an “Important” tag that is colored red, and a “Family” tag that is colored green.
Normally, events appear in the same color as the calendar they’re stored on. But you can override the event color by adding a colored tag to an event. If you add multiple colored tags to an event, the color of the first tag, sorted alphabetically, is applied.