If you want to add categorisation to the events in your platform, you can set event types via de taxonomies. /admin/structure/taxonomy/manage/event_types/overview
When the event type are enabled, your users can choose from them while creating or editing an event.
In the event overview and on the events tab on profile a filter is present to search for specific type of events.
As a site manager you can choose wether you want to make the event type field mandatory for users to choose from. This can be done via the event type setting: