The User object represents a User.

Organizations are the top level entity in the source application. Users are associated with an organization.

Attachments are the files associated with a ticket or a comment.

Comments represent the communication happening on a Ticket, both between a User and a Contact and the internal things like notes, private comments, etc. A Ticket can have one or more Comments.

Contact represent the external people you are in contact with. These could be customers, leads, etc. Contacts can be associated with an Account if the underlying product supports it.

Tags represent a common classification approach used in various ticketing systems. A Ticket may have one or more Tags associated with them.

Teams represent the grouping system used for Users. These are usually called groups, teams, agent groups, etc. in the underlying products. A User can belong to one or more Teams.

Core resource which represents some work that needs to be carried out. Tickets are usually mapped to issues, tasks, work items, etc. depending on the underlying product.

Users represent the people using the underlying ticketing system. They are usually called agents, team members, admins, etc.

Workspaces represent the top-level subdivision in a ticketing system. They usually have their own set of settings, tickets, statuses, priorities and users. Some of the usual terminologies used by the products for the top-level subdivision are projects, bases, spaces, workspace, etc. A Workspace could belong to an Organization.

Organization represents the company or the entity using the ticketing system. An Organization can have one or more Workspaces and Users.