Contributor is a helpful user account type for users doing cross-project collaboration. With this type you're now able to configure globally if users can view and modify all projects which they aren't a part of.
The Contributor user type has edit-access to all public Projects and Teams in the systems (as opposed to the Observer user type, who has view-only access to all public Projects and Teams, and regular Users, who have access only to Projects and Teams they are members of).
Contributor setting immediately provides a user with access to all public Projects in the system. To provide a limited access to selected Projects only, we recommend to introduce Observer Role instead.
Make a User a Contributor
Administrators can make others Contributors one by one. For this purpose they edit user type from the Account Settings tab of a user's details view.
Access to Data
If a Contributor user is not a project member, then her Default Role permissions are applied. If he is a project member, then her Project Role permissions are applied. When for an action Project Role permissions are more restrictive than Default Role permissions then the action is forbidden.
For example, when Default Role of a Contributor user has "Add Comment" permission enabled, then the user is allowed to submit comments to any entity in the system. The user cannot add comments to entities when he is a project member and her Project Role has "Add Comment" permission disabled.
Access to Views
Contributor setting does not influence access to Views. When a View is shared with Project or Team members only, then it is hidden for Contributors who are not members of the Project or the Team.