Open Google Calendar.
Open an event, or create a new one.
On the right, find the "Guests" section.
Start typing the name of the person and choose someone from your contacts. You can also type an email address to invite people who aren't in your contacts list.
To mark a guest as optional: Next to the guest's name, click the person's icon .
When you're done editing your event, click Save.
When you save your event, an email invitation will be sent to your guests.
You can use Find a Time to see if all invitees are available at the time you are suggesting.
You can also add a video call to a meeting to automatically create a clickable link for a Hangout meeting.