Within Teamwork Projects, when you add an event to your calendar, you can choose to add it as a particular event type so that you can filter the calendar to show just events of that type.

Note: To add or edit event types, you will need to be a site administrator.

In the calendar view, click the options button on the right and choose 'Edit Event Types':

You will see a screen listing any of the event types that you have already added to your site. When you hover over each one you will see a link to delete it:

To edit an event, just click on its name. You will then be able to change the name, and the color associated with the event:

You can also create new event types, by clicking the 'Add new event type' link at the bottom of the Event Types modal to create a new event type.

Click the 'Finish' button in the lower right when you are happy with your event types.

For more information, see: Creating an event in the calendar