Each and every card on Supernotes has the ability to be shared using a share code. By default cards do not have a share code.
You can generate a share code in the 'Sharing Options' of a card (third icon along the bottom). This code allows other users on Supernotes to join and interact with a card, with varying permissions.
The Code is comprised of four randomised English words like so,
Books Plane Phone Letter . And before you say 'That doesn't sound very secure', it actually results in an incredibly secure code, that would take current computers 185 years to crack (at 1000 guesses per second).
If you are the Author or a Moderator of a Card, you have the power to 'Freeze' the sharing ability of a card. This will prevent any new user from joining, and current members will be unaffected by this change.
To unfreeze the card, just click the button again.