Usually, when a candidate is scheduled for an interview, they'll receive a copy of the calendar invite in the form of an .ics file.
However, if your organization uses a calendar integration with Greenhouse Recruiting (such as Google Mail or Outlook), you can send these invites using a calendar integration so the candidate's response will display in Greenhouse Recruiting.
Candidate calendar events
Site Admins can enable connected calendar events by navigating to Configure > Permissions and selecting Send candidate calendar events via connected calendar integration in the Scheduling section.
Calendar integrations
After turning on candidate calendar invites, the candidate's response to interviews will be included on their candidate profile.
If you don't have an active calendar integration, your candidate invitations will revert to .ics files.