Department admin is a special role assigned by the system admin to some members of a department. Department admins can perform the following operations in a department after login to their own account:
1. Access to the libraries of the department
2. Manage(add or delete) members in their department
3. Manage(create/delete/rename) libraries in their department
4. Share a library to users or groups outside of this department. This is very useful for cross-department collaboration.
5. Set fine-grained permission to folders in the libraries for users or sub-departments in this department.
A normal member of the department can use the department just like a group. Each department is presented to its members as a group. A user can not only access to the libraries in the department he/she belongs to, but also the libraries in the parent departments of his/her department. The groups for departments are marked with a "building" icon 
next to its name. The only difference from groups is that, libraries owned by a user cannot be shared to a department group.