Assign User On The User Groups. Status "available" Means?


I have read this article regarding status of assigning users to a group

  • Assign the account to one of the available user groups on the User groups tab. A user’s membership in a user group is managed by the statuses:
    • Active—user belongs to the group.
    • Pending—user has applied for the groups and is waiting for approval.
    • Available—group is available for application.
    • Declined—user’s application was declined.

I dont really get it what is doing status Available?

What is the difference between Active and Available?

if the Settings -> General -> Allow customer to signup for user group setting is enabled, the groups with the Available status will be displayed to the customer and store-front. And he will be able to request these user groups