When you receive a meeting request from another Outlook user, the meeting appears on your calendar with your time scheduled, but shown as Tentative. Until you respond to the meeting request, the organizer doesn’t know whether you plan to attend. You can respond in one of four ways:
You can accept the request. Outlook deletes the meeting request and shows your time scheduled on your calendar as the meeting organizer indicated in the meeting request.
You can tentatively accept a request, indicating that you might be able to attend the meeting but are undecided. Outlook deletes the meeting request and shows your time on your calendar as tentatively scheduled.
You can propose a new meeting time. Outlook sends your request ...