Users Access Controls allows you to assign Users to Groups such as Customer, Manager, Programmer and configure the rights for each Group to control what they have access to.
Default Access Types
For projects/tasks/tickets/discussions you have next access types:
Full Access it means user can insert/edit/update/delete items
Manage Own Only user can manage (Create/Edit/Delete) items where he is assigned or owner.
it means user can view items only and can't manage it
View Own Only
it means user can view items where he is assigned only and can't manage it. So user will see projects where he is in team, will see tasks where he is assigned to, will see tickets with his department only and will see discussion where he is assigned to.
Custom Access option allows you configure Create/Edit/Delete actions separately