Your admins can set up custom chat fields to record extra information about chats. These work like Ticket Fields.
Users may be able to enter values for custom fields when they initiate the chat.
In this example, Nature of query is a custom field.
If your helpdesk has any custom chat fields, chats you view in the content pane have a Fields tab. Select it to view the custom fields.
Click the gear icon at upper right to edit the custom fields.