By default, users can start sending invites once they reach Trust Level 2.
The invite page can be accessed from the user menu:
Invites can be created from here, and it will also list any pending invites that have yet to be redeemed:
An invite can either be limited to an email address (which also gives the added option to include an optional message), or be used as a link that can be shared with up to 10 people.
In addition to the main invite section, invites can also be created from the ‘Share’ topic controls at the bottom of a topic:
This will also give the added option to ‘arrive at’ the specific topic once the invite has been accepted:
It’s only possible for non-staff users to invite people to a topic if the topic is in a public category.
When someone accepts an invite their ‘inviter’ will be recorded on their user summary page:
And there are also badges that can be earned for inviting more people to participate.
And I think that may be the long and short of it. Happy inviting! And please let me know if there’s anything I’ve missed out.