Make sure that you let people know if you can attend a meeting or event when you’ve been invited. When you get an invitation to an event, it appears on your calendar.
To reply to an invitation in Calendar:
Step 1: In the calendar grid, click the event.
Step 2: In the dialog box, select your response. Or, if you’d like to include a short note with your response, click More details, select your response, type your note, and click Save.
Step 3: You can change your response at any time by clicking More details > Add a note or change your response.
Step 4: You’ll also get an invitation in your email. If you’re using Gmail, you can respond to the invitation by clicking RSVP in your list of emails, or by clicking a response option in the email.