There are 3 types of privacy levels for contacts (both for people and organizations.)
The client details and work are public by default and everyone in the team has access to it.
Only the client team will have access to that private contact. The contact and their work will still show up in global search results, on worklists and on your Kanban board. Colleagues without access can still see the client and work names but no details or communication.
If you are assigned a task on a work item for a private contact, only the client team will be able to see that task on your to-do.
If someone who has not been granted access attempts to view a private item, they will see a message letting them know who to contact if they need access.
Only the client team will have access to the contact. Colleagues without access will not know the contact or work related to it exists in Karbon (it will not show up in the global search.)
If you are assigned a task, note or email on a hidden work item, only those with access to that work item will be able to see those tasks in your to-do list. Scheduled work for a hidden client will also be hidden.
To toggle between these privacy settings, go into the details tab of a contact, organization or work item, select edit and choose your level of privacy.