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So I am trying to use a public board but I do not want non team members to be able to do anything but read only access. Is this possible?
For public boards, only board-members will be able to edit or move any cards on that board, giving them essentially read-only access.
You will want to make sure to check the commenting permissions for the board, as it is possible to allow any Trello users to comment, even if they are not board members. You can change the boards settings from the boards menu, and you can read a bit more about that here: https://help.trello.com/article/791-changing-permissions-on-a-board