The auth module provides the login system.  Login requires a valid contact email address (contacts.email) 
and a password that corresponds to the hash (contacts.password_hash).  

The contact identified by their email address, must have been assigned a role of 'user' or'admin' in contacts_roles.
Therefore, session login requires the email and password of a contact who has a user or admin role.  

An admin login has unrestricetd system-wide access.  A user login has access to a subset of functions.  In general,
users cannot delete, cancel or remove settings, but can add, set and assign.  Users will often have Event support roles,
such as, recording volunteer registrations, checking on skills available and so on.

Admins may remove, delete or cancel if required and when requested by users.  The System Supervisor is an admin, who
also has access to the technical back-end, such as database maintenance, codebase maintenance, backups and so on.  
Hosting access is a requirement for this role.  Experience with phpMyAdmin and cPanel is mandatory.

