Google Calendar is the option to send email invitations to my events directly from my calendar. For example, when I schedule a meeting with three colleagues I simply put the meeting into my calendar then send invitations to those colleagues from my calendar event. My colleagues will receive email notifications of the event time, place, and any other details that I've added to the event's description. In the video embedded below I demonstrate how to send email invitations to Google Calendar events.
I'll cover topics like this one and many more in my upcoming online course Getting Going With GAFE. Three graduate credits are available for completing the course.