Invite is one option on Zoom app that is used to make instant and unscheduled meeting.

It is highly recommended to make zoom meetings in a scheduled manner(by scheduling a meeting).

But there are times you might need to make an instant zoom meeting and in order to do so we use the invite option of the Zoom app

To invite someone to a Zoom meeting, 

1. Open up your Zoom app.
2. Start a new meeting

3. Once the meeting starts you will be able to see a list of tabs on the bottom of the Zoom meeting window. 

Hit the invite tab

4. The invite tab will enable you to see

1.  Contacts tab to see a list of users  
2.  Zoom Rooms tab to see a list of rooms 
3. Email tab which you will be using to invite someone if S/he is not from splash

The Icons on each account's avatar will turn green if the user is online. But if the user is offline, the icons will be light base.

Note that if you are inviting a user to jump into a zoom call using the invite option, always, the user must be online.

5. Then you select a user/ a room that you want to invite to the meeting, provided that the user/ the room is online or not busy. Then hit Invite.

Note that rooms can also be invited from the contacts list.

That is it. You are done. The invitee will be able to see a Zoom call request on his Zoom app window. If answered, you are in an instant Zoom meeting.