Users have three different access levels. You can identify the current access level of a given user in the right column of their profile page:
An administrator is someone who is expected to manage the organization within the platform.
The administrator can use all functionality and view all content stored in the organization.
The only exception is tasks not explicitly associated with a team. These are only accessible by the creator and assignee. The tasks are stille available in searches and lists.
Admins can be managed by going to Organization > People > Administrators. You have to be an administrator in order to grant other people administrator priveligies.
A team member is someone who is expected to maintain team insight.
Team members can view and edit the information of all open teams, and any private teams they have been granted explicit access to.
They can also see the names of any private teams and who is granted access to those teams, but they can not view the contents of those teams unless they have been explicitly granted access themselves.
A collaborator is someone who collaborates with, has input to or is interested in the work carried out by the team. Typical use cases include representatives from clients, vendors or partners.
A collaborator can view, search and comment on all of the team's content, assign and perform tasks, and create observations and achievements.
Teams have two different access levels. You can identify private teams by the padlock displayed next to the team name.
This is the default state when creating a team. Private teams are accessible by admins and users granted explicit access to the team.
When creating or editing a team, you can choose to make the team open.
An open team will have its contents viewable and searchable to any user in the organization.
To make an existing team open, navigate to said team, click the icon in the top right corner, and select "Edit". Then, check off the "Open team" checkbox.